一定 yī dìng
“surely; certainly; necessarily”
adverb, attributiveHSK 3 · 2021 list level 2
新HSK等级2025 HSK 3.0 syllabus level
一定 appears in the November 2025 exam syllabus in the following numbered entry. Levels refer to the listed reading and use, not every meaning.
- Entry 924: 一定 yídìng — Level 3; official annotation 3 (形、副). PDF page 103
Separate from the HSK 2.0 and 2021 list labels above. Compare the three lists.
用法How to use 一定
一定 means "surely" or "definitely" and is used as an adverb to show strong certainty. It usually comes after the subject and before the verb or adjective, often in patterns like 一定会, 一定是, or 一定要. The negative form 不一定 means "not necessarily."
例句Example sentences
- 明天你一定要来。míng tiān nǐ yí dìng yào lái.You must definitely come tomorrow.
- 他一定是医生。tā yí dìng shì yī sheng.He must be a doctor.
- 你放心，我一定帮你。nǐ fàng xīn, wǒ yí dìng bāng nǐ.Don't worry, I will definitely help you.
常见错误Common mistakes
-
✗一定我帮你。
✓我一定帮你。
一定 is an adverb and normally comes after the subject, before the verb.
易混词Easily confused
一定vs必须
必须 means "must" (obligation); 一定 means "surely/definitely" (certainty). To express "must" with 一定, use 一定要.