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Help the teenager complete their brilliant survival plan.

If zombies ___ our school, I would immediately barricade myself inside the cafeteria.

The correct answer is attacked.

This is a second conditional sentence, which we use to talk about unlikely or hypothetical situations in the present or future. We use the past simple tense ("attacked") in the "if" clause, and "would" + base verb in the main clause.

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Conditional Sentence

As is typical for many languages, full conditional sentences in English consist of a condition clause or protasis specifying a condition or hypothesis, and a consequence clause or apodosis specifying what follows from that condition. The condition clause is a dependent clause, most commonly headed by the conjunction if, while the consequence is contained in the main clause of the sentence. Either clause may appear first.

Different types of conditional sentences (depending largely on whether they refer to a past, present or future time frame) require the use of particular verb forms (tenses and moods) to express the condition and the consequence. In English language teaching the most common patterns are referred to as first conditional, second conditional and third conditional; there is also a zero conditional and mixed conditional.

Humor

Humor is subjective, but at least the author tried.

Simple Past

The simple past, past simple or past indefinite, sometimes called the preterite, is the basic form of the past tense in Modern English. It is used principally to describe events in the past, although it also has some other uses. Regular English verbs form the simple past in -ed; however there are a few hundred irregular verbs with different forms.

The term "simple" is used to distinguish the syntactical construction whose basic form uses the plain past tense alone, from other past tense constructions which use auxiliaries in combination with participles, such as the past perfect and past progressive.

Formation

Regular verbs form the simple past end*-ed*; however there are a few hundred irregular verbs with different forms. For details see.

Most verbs have a single form of the simple past, independent of the person or number of the subject (there is no addition of -s for the third person singular as in the simple present).

However, the copula verb be has two past tense forms: was for the first and third persons singular, and were in other instances.

The form were can also be used in place of was in conditional clauses and the like; for information on this, see subjunctive.

This is the only case in modern English where a distinction in form is made between the indicative and subjunctive moods in the past tense.

Questions, other clauses requiring inversion, negations with not, and emphatic forms of the simple past use the auxiliary did.

A full list of forms is given below, using the (regular) verb help as an example:

  • Basic simple past:
    • I/you/he/she/it/we/they helped
  • Expanded (emphatic) simple past:
    • I/you/he/she/it/we/they did help
  • Question form:
    • Did I/you/he/she/it/we/they help?
  • Negative:
    • I/you/he/she/it/we/they did not (didn't) help
  • Negative question:
    • Did I/you/he/she/it/we/they not help? / Didn't I/you/he/she/it/we/they help?

Usage

The simple past is used for a single event (or sequence of such events) in the past, and also for past habitual action:

  • He took the money and ran.
  • I visited them every day for a year.

It can also refer to a past state:

  • I knew how to fight even as a child.

For action that was ongoing at the time referred to, the past progressive is generally used instead (e.g. I was cooking). The same can apply to states, if temporary (e.g. the ball was lying on the sidewalk), but some stative verbs do not generally use the progressive aspect at all, and in these cases the simple past is used even for a temporary state:

  • The dog was in its kennel.

However, with verbs of sensing, it is common in such circumstances to use could see in place of saw, could hear in place of heard, etc.

  • I felt cold.

If one action interrupts another, then it is usual for the interrupted (ongoing) action to be expressed with the past progressive, and the action that interrupted it to be in the simple past:

  • Your mother called while you were cooking.

The simple past is often close in meaning to the present perfect.

The simple past is used when the event happened at a particular time in the past, or during a period which ended in the past (i.e. a period that does not last up until the present time).

This time frame may be explicitly stated, or implicit in the context (for example the past tense is often used when describing a sequence of past events).

  • I was born in 1980.
  • We turned the oven off two minutes ago.
  • I came home at 6 o'clock.
  • When did they get married?
  • We wrote two letters this morning.
  • She placed the letter on the table, sighed, and left the house.Contrast these examples with those given at.

Note also that for past actions that occurred before the relevant past time frame, the past perfect is used.

Various compound constructions exist for denoting past habitual action.

The sentence When I was young, I played football every Saturday might alternatively be phrased using used to (... I used to play ...) or using would (... I would play...).

The simple past also has some uses in which it does not refer to a past time.

  • If he walked faster, he would get home earlier.
  • I wish I knew what his name was.

These are generally in condition clauses and some other dependent clauses referring to hypothetical circumstances, as well as certain expressions of wish:

  • He said he wanted to go on the slide.

Past Progressive

The past progressive or past continuous construction combines progressive aspect with past tense, and is formed using the past tense of be (was or were) with the present participle of the main verb.

It indicates an action that was ongoing at the past time being considered:

  • At three o'clock yesterday, I was working in the garden. For stative verbs that do not use the progressive aspect, the simple past is used instead (At three o'clock yesterday we were in the garden).

The past progressive is often used to denote an action that was interrupted by an event, or for two actions taking place in parallel:

  • While I was washing the dishes, I heard a loud noise.
  • While you were washing the dishes, Sue was walking the dog.(Interrupted actions in the past can also sometimes be denoted using the past perfect progressive.)

The past progressive can also be used to refer to past action that occurred over a range of time and is viewed as an ongoing situation:

  • I was working in the garden all day yesterday. That could also be expressed using the simple past, as I worked..., which implies that the action is viewed as a unitary event (although the effective meaning is not very different).

Past Perfect

The past perfect, sometimes called the pluperfect, combines past tense with perfect aspect; it is formed by combining had (the past tense of the auxiliary have) with the past participle of the main verb.

It is used when referring to an event that took place prior to the time frame being considered.

This time frame may be stated explicitly, as a stated time or the time of another past action:

  • We had finished the job by 2 o'clock.
  • He had already left when we arrived.

The time frame may also be understood implicitly from the previous or later context:

  • I was eating ... I had invited Jim to the meal but he was unable to attend. (i.e. I invited him before I started eating)
  • I had lost my way. (i.e. this happened prior to the time of the past events I am describing or am about to describe)

Compare He had left when we arrived (where his leaving preceded our arrival), with the form with the simple past, He left when we arrived (where his leaving was concurrent with or shortly after our arrival).

Note that unlike the present perfect, the past perfect can readily be used with an adverb specifying a past time frame for the occurrence.

For example, while it is incorrect to say I have done it last Friday (the use of last Friday, specifying the past time, would require the simple past rather than the present perfect), there is no such objection to a sentence like "I had done it the previous Friday".

The past perfect can also be used for states or repeated occurrences pertaining over a period up to a time in the past, particularly in stating "for how long" or since when". However, if the state is temporary and the verb can be used in the progressive aspect, the past perfect progressive would normally be used instead. Some examples with the plain past perfect:

  • I had lived in that house for 10 years.
  • The children had been in their room since lunchtime.

Past Perfect Progressive

The past perfect progressive or past perfect continuous (also known as the pluperfect progressive or pluperfect continuous) combines perfect progressive aspect with past tense.

It is formed by combining had (the past tense of auxiliary have), been (the past participle of be), and the present participle of the main verb.

Uses of the past perfect progressive are analogous to those of the present perfect progressive, except that the point of reference is in the past.

For example:

  • I was tired because I had been running.
  • By yesterday morning they had already been working for twelve hours.
  • Among the witnesses was John Smith, who had been staying at the hotel since July 10.

This form is sometimes used for actions in the past that were interrupted by some event (compare the use of the past progressive as given above).

For example:

  • I had been working on my novel when she entered the room to talk to me.

This implies that I stopped working when she came in (or had already stopped a short time before); the plain past progressive (I was working...) would not necessarily carry this implication.

If the verb in question does not use the progressive aspect, then the plain past perfect is used instead.

The past perfect progressive may also have additional specific uses similar to those of the plain past perfect.

Verb

A verb is a word that expresses an action, a state, or an occurrence — and it's the engine of every English sentence. Understanding how verbs work is foundational to everything else in English grammar, from forming questions to building complex sentences.

Verb Forms

Most English verbs have five inflected forms:

  • Base form (go, write, climb) — used as an infinitive, imperative, present subjunctive, and present indicative in all persons except third-person singular.
  • -s form (goes, writes, climbs) — used for the present tense, third-person singular (she writes).
  • Past tense (went, wrote, climbed) — also called the preterite.
  • Past participle (gone, written, climbed) — identical to the past tense for regular verbs, but often different for irregular verbs.
  • -ing form (going, writing, climbing) — serves as the present participle and gerund.

The verb be is a special case with more forms than any other English verb (am, is, are, was, were, been, being). Modal verbs like can, must, and should have fewer forms than typical verbs.

Main Verbs and Auxiliaries

Verbs in English often appear in combinations: one or more auxiliary verbs paired with a main verb.

  • The dog was barking very loudly.
  • My hat has been cleaned.
  • Jane does not really like us.

The first verb in the combination is the finite verb (it carries tense and agrees with the subject). The rest are nonfinite (infinitives or participles). Notice that these verbs don't always sit next to each other — as in does not really like.

Tense, Aspect, and Mood

English expresses tense (time reference), aspect (how an action unfolds over time), and mood (the speaker's attitude toward the action) mostly through verb combinations rather than word endings. That's why you'll encounter labels like "present progressive" or "conditional perfect" — these are specific tense–aspect–mood combinations built with auxiliaries.

Self-check: If you can change the time of a sentence by swapping one word (She runs → She ran), that word is the verb.

Keep Practising

To build your verb skills from the ground up, try these challenges: Basics. "To be" in Present Tense, Basics. Common Uses of Auxiliary Verbs, and Transitive and Intransitive Verbs.

Present

Present tense is used, in principle, to refer to circumstances that exist at the present time (or over a period that includes the present time) and general truths. However the same forms are quite often also used to refer to future circumstances, as in "He's coming tomorrow" (hence this tense is sometimes referred to as present-future or nonpast). For certain grammatical contexts where the present tense is the standard way to refer to the future, e.g., conditional sentences and dependent clauses. It is also possible for the present tense to be used when referring to no particular real time (as when telling a story), or when recounting past events (the historical present, particularly common in headline language). The present perfect intrinsically refers to past events, although it can be considered to denote primarily the resulting present situation rather than the events themselves.

The present tense has two moods, indicative and subjunctive; when no mood is specified, it is often the indicative that is meant. In a present indicative construction, the finite verb appears in its base form, or in its -s form if its subject is third-person singular. (The verb be has the forms am, is, are, while the modal verbs do not add -s for third-person singular.)

Past

Past tense forms express circumstances existing at some time in the past, although they also have certain uses in referring to hypothetical situations (as in some conditional sentences, dependent clauses and expressions of wish). They are formed using the finite verb in its preterite (simple past) form.

Certain uses of the past tense may be referred to as subjunctives; however the only distinction in verb conjugation between the past indicative and past subjunctive is the possible use of were in the subjunctive in place of was.

Note also that in certain contexts past events are reported using the present perfect.

Future

English is sometimes described as having a future tense, although since future time is not specifically expressed by verb inflection, some grammarians identify only two tenses (present or present-future, and past). The English "future" usually refers to a periphrastic form involving the auxiliary verb will (or sometimes shall when used with a first-person subject). There also exist other ways of referring to future circumstances, including the going to construction, and the use of present tense forms. For particular grammatical contexts where the present tense substitutes for the future, see conditional sentences and dependent clauses. For discussion and comparison of the various ways of making future reference in English, see going-to future.

For specific uses of future constructions formed with will/shall, see future.

Future-in-the-past

A "future-in-the-past" tense (or form) is sometimes referred to. This takes essentially the same form as the conditional, that is, it is made using the auxiliary would (or sometimes should in the first person).

This form has a future-in-the-past meaning in sentences such as She knew that she would win the game. Here the sentence as a whole refers to some particular past time, but would win refers to a time in the future relative to that past time.

Simple

"Simple" forms of verbs are those appearing in constructions not marked for either progressive or perfect aspect (I go, I don't go, I went, I will go, etc., but not I'm going or I have gone).

Simple constructions normally denote a single action (perfective aspect), as in Brutus killed Caesar, a repeated action (habitual aspect), as in I go to school, or a relatively permanent state, as in We live in Dallas. They may also denote a temporary state (imperfective aspect), in the case of stative verbs that do not use progressive forms.

B1 | Intermediate

B1 is the intermediate level of the Common European Framework of Reference for Languages (CEFR). It marks the point where you move beyond survival English and start expressing yourself with real independence — describing experiences, explaining opinions, and handling everyday situations without a script.

What a B1 user can do

At this level, you're expected to:

  • Understand the main points of clear, standard speech and writing on familiar topics — work, school, travel, hobbies.
  • Handle most travel situations in English-speaking environments.
  • Produce simple connected text on topics you know or care about.
  • Describe experiences, events, hopes, and plans, and give brief reasons and explanations for your opinions.
  • Communicate in routine tasks that require a straightforward exchange of information.

What B1 grammar looks like

B1 is where grammar starts to get more layered. You're not just forming basic sentences anymore — you're combining ideas, using different tenses with more precision, and starting to handle structures like the passive voice, modal verbs for necessity and possibility, and gerunds vs. infinitives. You're also expected to build complex sentences with linking words and dependent clauses.

Typical B1 grammar areas include:

  • Future tenses — distinguishing will, going to, and the present continuous for future plans
  • Passive voiceThe report was written yesterday.
  • Modal verbsYou should apply early. / She might be late.
  • Used toI used to live in Berlin.
  • Verb patterns — knowing whether a verb takes a gerund, an infinitive, or both (I enjoy reading vs. I decided to leave)

What B1 doesn't mean

B1 speakers still hesitate, make grammatical errors, and sometimes struggle with less familiar topics. That's normal. The key difference from A2 is that you can keep a conversation going and get your point across even when things aren't perfect. The step up to B2 involves handling more abstract topics, understanding nuance, and producing more complex, accurate language.

Self-check: Can you tell a friend about a recent trip — what happened, what you liked, and what you'd do differently — without switching to your native language? If yes, you're likely operating at B1 or above.

Ready to find out where you stand? Try Are you B1/Intermediate? Test your English CEFR Level to figure out!, then build your skills with challenges like Basics. Passive Voice, Basics. Modal verbs, and Used to.

Difficulty: Medium

Medium difficulty. Difficulty levels represent author's opinion about how hard a question or challenge is.