The correct answers are: The commander ordered the humans to explain how the spaceship worked and asked if they had any fuel left. The commander instructed the humans to explain how the spaceship worked and wanted to know whether they had any fuel left.
The original quote contains an embedded question ("how this spaceship works") inside a command. In reported speech, the embedded question must backshift its tense ("how the spaceship worked") but must never use auxiliary inversion like "how did the spaceship work".
Furthermore, the yes/no question ("Do you have any fuel left?") must be introduced by if or whether and follow standard subject-verb word order ("if they had"). Options using "asked did they have" are incorrect because they retain the direct question auxiliary did. Finally, "commanded the humans explain" is missing the required to before the infinitive.
Indirect speech
- Direct: "I am tired." → Indirect: She said she was tired. (present → past)
- Direct: "I will come." → Indirect: He said he would come. (will → would)
- Direct: "I have finished." → Indirect: She said she had finished. (present perfect → past perfect)
- today → that day; here → there; tomorrow → the next day
Indirect speech reports someone's words without quotation marks. The mechanism: backshift tenses one step into the past, shift pronouns, and adjust time/place expressions.
Rule: if the reporting verb is past (said, told, asked), shift the reported tense back one step. If the reporting verb is present (says), no shift needed.
Imperative mood
- ✅ Sit down. — command (bare verb, no subject)
- ✅ Don't touch that. — negative imperative
- ✅ Let's go. — first-person inclusive imperative
- ❌ You sit down. — adding you sounds aggressive (only for emphasis/anger)
The imperative mood uses the bare verb form with no stated subject for commands, instructions, requests, and invitations. Negated with don't. Softened with please or replaced by questions (Could you…?) for politeness.
Rule: imperative = base form of verb, no subject, no tense marking. If there's a subject or tense → it's not imperative.
Questions
- ✅ Do you like coffee? — do-support (no existing auxiliary)
- ✅ Can she swim? — inversion (auxiliary before subject)
- ✅ Where does he live? — wh-question
- ✅ You're coming, aren't you? — tag question
Questions require inversion (auxiliary before subject) or do-support (add do/does/did). Types: yes/no (Do you…?), wh- (What/Where/When…?), negative (Don't you…?), tag (…isn't it?).
Rule: find the auxiliary. Move it before the subject. No auxiliary? Add do/does/did. Never use just intonation in written English (You like coffee? is not standard).
Word order
- ✅ She (S) eats (V) cake (O). — standard SVO
- ❌ Cake eats she. — SOV (not English)
- ✅ a lovely little old rectangular green French silver whittling knife — adjective order (opinion→size→age→shape→colour→origin→material→purpose)
- ✅ Never have I seen… — inversion after negative adverb
English word order = SVO (subject-verb-object) as default. Adjectives follow a fixed sequence (opinion→size→age→shape→colour→origin→material). Adverb placement varies by type. Deviations signal questions, emphasis, or literary style.
Rule: when in doubt, default to SVO. English position = meaning. Move a word and you change the grammar or the emphasis.
Verb tense
| Simple | Progressive | Perfect | Perfect Progressive | |
|---|---|---|---|---|
| Past | worked | was working | had worked | had been working |
| Present | work(s) | am working | have worked | have been working |
| Future | will work | will be working | will have worked | will have been working |
Verb tense = time (past/present/future) × aspect (simple/progressive/perfect) = 12 forms. Each slot has a specific job — not just "when" but "how the action relates to its time frame."
Key insight: most learners don't need all 12 at once. Simple covers 80% of communication. Add perfect and progressive as needed.
C1 | Advanced
- ✅ Not only did she finish early, but she also helped others. — inversion for emphasis
- ✅ It is the process that matters, not the result. — cleft sentence
- ✅ I insist that he be present. — formal subjunctive
- ✅ Were I to disagree, I would say so. — inverted conditional
These are C1 structures — the CEFR advanced level. At C1 you control inversion, cleft sentences, subjunctive forms, and register-switching fluently across formal and informal contexts.
Marker: if you can restructure a sentence for rhetorical effect without hesitation, you're C1.
Hard
- Had she not intervened, the situation would have escalated. — inverted conditional
- All distractors are grammatically plausible in other contexts
- Multiple rules interact (e.g., tense + aspect + modality)
- Context determines the answer — no single "rule" is enough
Hard marks upper-intermediate to advanced challenges: B2+, interacting rules, edge cases, plausible distractors, and contexts where pattern-matching fails.
Use "Hard" when Easy/Medium feel trivial and you want to test whether you actually understand a rule versus just recognising surface patterns.