The sentence requires the present perfect tense to express an action completed in the past with relevance to the present. The correct form for the plural subject "the students" is "have done."
Verb
A verb is a word that expresses an action, a state, or an occurrence — the engine of every English sentence. Most verbs have five forms: base (go), -s form (goes), past tense (went), past participle (gone), and -ing form (going). The verb be is the major exception with eight forms; modal verbs like can and must have fewer.
Verbs carry tense (when), aspect (how it unfolds), mood (the speaker's attitude), and voice (active vs passive). Mastering them is foundational — virtually every other grammar topic depends on getting verbs right.
Present tense
The present tense in English has four forms: simple present (I work) for habits, general truths, and stative descriptions; present progressive (I am working) for actions happening right now or temporary situations; present perfect (I have worked) for past actions with present relevance; and present perfect progressive (I have been working) for ongoing actions continuing into the present.
The simple/progressive distinction is one of the trickiest jumps for learners — I work in Paris (habitual) and I'm working in Paris (temporary, right now) feel almost identical but signal different things. Pick wrong and your meaning subtly shifts.
Perfect tense
The perfect aspect marks an action as complete relative to a point in time. It's formed with have + past participle: I have eaten (present perfect), She had finished (past perfect), They will have arrived (future perfect). The perfect doesn't just say when — it says the action's completion is relevant to the time of reference.
The trickiest English-specific use is the present perfect: I have lived in Paris connects the past to now (you may still live there), while I lived in Paris doesn't. This connection is one of the biggest jumps for learners whose native language doesn't make the same distinction.
A2 | Elementary | Pre-intermediate
A2 is the elementary level in the CEFR framework, sitting between A1 and B1. At A2 you can handle routine exchanges — ordering food, asking directions, making small talk — and describe your immediate environment in simple sentences.
Grammatically, A2 introduces past simple and past continuous, present perfect for experiences, basic modal verbs, and the first conditional. You're also picking up collocations and learning which verbs take gerunds vs. infinitives. Knowing your level here is the difference between confident progress and frustration: A2 material consolidates the basics; B1 will overwhelm you.
Difficulty: Easy
The Easy difficulty tag marks questions and challenges aimed at beginners — typically A1 or early A2 level. Expect single-rule focus, short sentences, common everyday vocabulary, and one clear correct answer. Distractors usually rule themselves out quickly.
Filter by Easy when you're rebuilding fundamentals, warming up before harder material, or testing whether you've truly internalised a basic rule before moving on. Easy doesn't mean trivial — it means the rule itself is unambiguous and the context doesn't pile on extra complications.