HSK 2
能愿动词：该、应该
néng yuàn dòng cí ： gāi 、 yīng gāi
Modal verbs: 该, 应该 (should, ought to)
Explanation
该 (gāi) and 应该 (yīnggāi) are both modal verbs (verbs of mood such as 会, 能, 想... placed before the main verb), meaning 'should, ought to', used to give advice or talk about obligation.
Subject (the person or thing performing the action, at the start of the sentence) + 该/应该 gāi/yīnggāi + Verb.
你该吃药了 (You should take your medicine now).
When advising someone to do something they ought to do, reminding them of a duty, or stating what is reasonable by common sense. 该 leans toward spoken language, a gentle everyday reminder; 应该 is more formal and complete, often used when talking about responsibility.
该 gāi usually comes with 了 le at the end to signal 'the time has come' (你该走了 - you should go now); 应该 yīnggāi stresses what is right and proper (你应该帮助他 - you should help him).
Vietnamese learners often forget that a VERB must follow 该/应该, not placing a noun directly after it; and they easily omit the sentence-final 了 le with 该 when wanting to express 'the time has come'.
Examples
You should take your medicine now.
You all should go and have a health check-up.
Practice
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Learn “能愿动词：该、应该” effectively
The grammar point “能愿动词：该、应该” (Modal verbs: 该, 应该 (should, ought to)) is one of the key structures at HSK 2. To use it fluently, you need to understand the contexts where it's used and practice regularly.
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