应该: should, ought to
能愿动词 / modal verbs
Tone colorsā tone 1á tone 2ǎ tone 3à tone 4a neutral
Subject + (不) 应该 + Verb
应该 (yīnggāi) expresses what is normal, advisable or right: "you should", "one ought to". It's softer than 得 (děi) and very common for advice.
Negative: 不应该 = "shouldn't". Question: 应该不应该…？ or 应该…吗？
应该 can also express a confident assumption: 他应该到了 ("he should have arrived by now").
Examples
你应该多喝水，多休息。
Nǐ yīnggāi duō hē shuǐ, duō xiūxi.You should drink plenty of water and rest a lot.
感冒了，不应该去游泳。
Gǎnmào le, bù yīnggāi qù yóuyǒng.With a cold, you shouldn't go swimming.
我们应该几点出发？
Wǒmen yīnggāi jǐ diǎn chūfā?What time should we leave?
现在七点，他应该到家了。
Xiànzài qī diǎn, tā yīnggāi dào jiā le.It's seven now, he should be home.
Common mistakes
应该 goes before the verb: ✗ 你休息应该 → ✓ 你应该休息.
For a firm prohibition, 不能 or 别 is more natural: 这儿不能抽烟.