Modal Verbs: 该 & 应该
能愿动词：该/应该
Express obligation and what someone should do using 该 and 应该
Place 该 or 应该 before the verb to express "should" or "ought to." 应该 is more formal; 该 is colloquial and often used in spoken Chinese.
该 is shorter and more casual — perfect for daily conversation. 应该 carries more weight and formality. Both mean "should" but the tone differs.
Lesson Targets
Podcast
Podcast: Modal Verbs: 该 & 应该 (能愿动词：该/应该)
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Understanding 能愿动词：该/应该
Every language needs a way to say "you should." In Chinese, 应该 and 该 are your tools. 应该 is the full, standard form — you will see it in textbooks, hear it in news, and read it in formal writing. 该 is the colloquial cousin — shorter, snappier, and the one your Chinese friends actually use in casual conversation. Think of 应该 as "you should" and 该 as "you oughta." They are interchangeable in most situations, but 该 feels warmer and more personal. The negative 不应该 means "should not" and carries a mild scolding tone — a parent might say 你不应该说那样的话 (You should not say things like that). There is also the pattern 该……了 which means "it is time to…" — as in 该吃饭了 (Time to eat!). You will see this pattern constantly in daily life.
Key Points
- 应该 (yīnggāi) = "should / ought to" — standard and slightly formal.
- 该 (gāi) = "should / ought to" — casual, spoken Chinese.
- Negative: 不应该 / 不该 = "should not" — carries a mild reproach.
- 该……了 = "it is time to…" — extremely common in daily life (see GP-80).
- 应该 can also express probability: 他应该到了 (He should have arrived by now).
- In advice-giving, 应该 sounds more authoritative than 可以.
- 该 is often heard from parents: 该睡觉了！(Time for bed!), 该做作业了！(Time to do homework!)
Chinese culture places great value on proper behavior and fulfilling obligations. Using 应该 correctly shows you understand social expectations — 你应该尊重老师 (You should respect teachers) is a common phrase reflecting Confucian values.
Key Vocabulary
Example Sentences
你该吃药了。
You should take your medicine now.
Casual — a family member reminding you
你们应该去检查一下儿身体。
You should go get a physical checkup.
More formal advice
我们不应该浪费时间。
We should not waste time.
天冷了，你该穿厚一点儿。
It is cold — you should dress warmer.
学生应该认真学习。
Students should study earnestly.
他现在应该到家了。
He should be home by now.
Expressing probability / expectation
你不该这样说话。
You should not speak like that.
我们该走了。
We should get going. / It is time for us to leave.
Common Mistakes
The negation 不 goes BEFORE 应该, not after it. "Should not go" = 不应该去.
The pattern 该……了 needs 了 at the end to express "it is time to…" The 了 signals the change of state.
Practice Exercises
Tips & Tricks
In daily conversation, 该 is much more common than 应该. Use 该 with friends and family.
The pattern 该……了 is one of the most useful phrases in Chinese — practice it with daily routines: 该吃饭了, 该上课了, 该走了.
When 应该 expresses probability ("should have by now"), it is similar to English: He should be here = 他应该在这儿.
Do not confuse 该 with 要 — both can mean "should" in some contexts, but 该 is about obligation while 要 is about desire or necessity.
Homework
Write your daily routine using 该……了 sentences: 七点了，该起床了。八点了，该上课了。Add at least six time-based "it is time to" sentences.
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