MOdAL verbS
12.412.4 expressing obligations
Obligations may be strong (must) or weak (should). In Mandarin, as in English, negation
often changes the force of the words used to express obligation. This section presents a brief
overview of the use of modal verbs to express obligations. For more on expressing obligations,
see Chapter 50.12.4.1 Strong obligation: must, have to
The Mandarin words used to indicate strong obligation (must) are 必须/必須 bìxū, 必得 bìděi,
and 得 děi. 必得 bìděi and 必须/必須 bìxū are more formal than 得 děi. 必须/必須 bìxū is
used in legal pronouncements and in other formal spoken and written contexts.
必须/必須 bìxū婚前必须做健康检查。
婚前必須做健康檢查。
Hūn qián bìxū zuò jiànkāng jiǎnchá.
Before you get married you must have a physical exam.
必得 bìděi医生说我每天必得吃药。
醫生說我每天必得吃藥。
Yīshēng shuō wǒ měitiān bìděi chī yào.
The doctor says I must take medicine every day.
得 děi住院以前得先付钱。
住院以前得先付錢。
Zhù yuàn yǐqián děi xiān fù qián.
Before being admitted to the hospital you must first pay a fee.
C50.1.112.4.2 weak obligation – social and moral obligation: should, ought to
The modal verbs used to express weak obligations (should) associated with social or moral
responsibilities include 应该/應該 yīnggāi, 该/該 gāi, 应当/應當 yīngdāng, and 当/當 dāng.
应当/應當 yīngdāng is more formal than 应该/應該 yīnggāi and can be used in formal texts
including legal documents. 该/該 gāi is used in informal speech. 应/應 yīng is used in formal
texts including legal documents. For illustrations of legal uses, seeC50.1.2
应该/應該 yīnggāi学生应该认真地学习。
學生應該認真地學習。
Xuésheng yīnggāi rènzhēn de xuéxí.
Students should study conscientiously.
该/該 gāi你该早一点睡觉。
你該早一點睡覺。
Nǐ gāi zǎo yīdiǎn shuì jiào.
You should go to sleep a little earlier.