necessary/'nesəsərɪ $ -serɪ/

a. needed in order to have sth or do sth

a. 必需的，必要的：[it is necessary (for sb) to do sth] It is necessary for you to take an umbrella. 你有必要带一把伞。

◇[necessary for (或to) sb/sth] Food is necessary for life. 食物是生命所需要的。

if necessary 如果有必要的话：We can change the date of the meeting, if necessary. 如果有必要的话，我们可以改变会议日期。

构词源自need

音组-ary/-ərɪ $ -erɪ/

arbitrary; dictionary; literary; necessary; ordinary; secretary; temporary; voluntary

常犯错误

✗You are necessary to act fast.

✓ It is necessary for you to act fast. 你必须动作快点。