[Learn basic Chinese with grammar] How to use 得, 應該, and 必須 for obligation

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Obligation in Chinese

In Chinese, 得 ♬, 應該 ♬, and 必須 ♬ can all express obligation, but the strength is different.

Word	Basic meaning	Feeling
得 děi ♬	have to	practical need
應該 ♬	should	advice or expectation
必須 ♬	must	strong rule or requirement

Here, 得 is pronounced děi ♬. It means “have to” and shows that something is necessary because of the situation. This is different from the common grammar particle 得, which is usually pronounced de ♬ and is used after verbs, as in 說得好 or 跑得快.

1. 得 děi: have to

Use 得 ♬ when something is necessary because of the situation. It often sounds natural in daily speech.

Pattern	Meaning
Subject + 得 děi + Verb	Subject has to do something

Chinese	English
我得查一下地址。 ♬	I have to check the address.
他得早點出門。 ♬	He has to leave earlier.

2. 應該: should

Use 應該 ♬ when you think something is the right thing to do. It is often used for advice, expectation, or a reasonable guess.

Pattern	Meaning
Subject + 應該 + Verb	Subject should do something

Chinese	English
你應該休息一下。 ♬	You should rest for a bit.
我們應該先確認細節。 ♬	We should confirm the details first.

應該 is usually softer than 必須.

3. 必須: must

Use 必須 ♬ for strong obligation. It often appears in rules, work situations, and important requirements.

Pattern	Meaning
Subject + 必須 + Verb	Subject must do something

Chinese	English
申請人必須填寫表格。 ♬	Applicants must fill out the form.
訪客必須出示證件。 ♬	Visitors must show ID.

必須 sounds stronger and more formal than 得.

4. Simple comparison

Chinese	English	Feeling
我得修改密碼。 ♬	I have to change the password.	The situation requires it
我應該修改密碼。 ♬	I should change the password.	It is a good idea
我必須修改密碼。 ♬	I must change the password.	Strong requirement

Useful words and example sentences