Complete the frustrated roommate's text message about a terrible singer.
I can literally feel the floorboards ___ every time Kevin tries to hit a high note!
The correct answer is shake.
With verbs of physical perception like feel, we use the bare infinitive (the base verb without "to") to describe a complete, repeated action or fact.
A very common mistake is adding "to" before the verb, but remember: verbs of perception are allergic to the word "to"!
Verb
Verb vs noun vs adjective: nouns name things. Adjectives describe. Verbs express what happens or what IS. The test: can it take tense (walked, will walk)? Can it take -ing? Can it follow to as an infinitive (to walk)? Yes to any → verb. English often converts freely between classes (run = noun or verb), so context decides.
A verb = action/state/occurrence word. 5 forms (base, -s, past, past participle, -ing). Carries tense, aspect, mood, voice. The one required element in every sentence.
Diagnostic: does it change for tense (walk → walked)? Can you put to before it (to walk)? Does it take -ing (walking)? → verb.
Infinitive
Infinitive vs gerund: the #1 verb-pattern confusion. Some verbs take only infinitive (want to go ✅), some only gerund (enjoy going ✅), some both with different meanings (stop to smoke ≠ stop smoking). No logical rule exists — learn by verb.
The infinitive = base verb form used non-finitely. To-infinitive (to go) after certain verbs. Bare infinitive (go) after modals and causatives.
Diagnostic: what's the main verb? Check whether it takes to-infinitive, bare infinitive, or gerund. If unsure, try both and see which sounds natural to native speakers.
Object
Object vs subject: the subject does the action; the object receives it. The cat (subject) chased the mouse (object). In English, word order (SVO) determines which is which — subject before verb, object after.
An object is the entity a verb acts upon: direct (I read the book), indirect (I gave her a book), or prepositional (I waited for him).
Diagnostic: ask "[verb] what/whom?" after the verb. The answer is the direct object. Ask "to/for whom?" for the indirect object. After a preposition? Prepositional object.
B1 | Intermediate
B1 vs B2: B1 handles standard everyday communication and simple opinions. B2 handles abstract topics, sustained arguments, and nuanced register. If you can chat about your life but struggle to debate an issue or write a formal essay, you're B1.
B1 is the intermediate CEFR level: independent handling of familiar topics, second conditional, basic passive, reported speech, and linking words for cause and contrast.
Diagnostic: can you read a newspaper article on a familiar topic and summarise the argument? Comfortably → B2. Struggle with abstractions → still B1.
Medium
Medium vs Easy: Easy has one obviously correct answer and clearly wrong distractors. Medium has one correct answer but plausible distractors — you need to actually know the rule, not just guess from sound.
The Medium tag filters for A2–B1 challenges with realistic difficulty: one rule per question, plausible alternatives, everyday contexts.
Diagnostic: if you're scoring 90%+ on Easy, move here. If you're below 60% on Medium, go back to Easy for that topic. Target 70–80% accuracy for maximum learning.