imperative

剑桥词典

imperative adjective (URGENT)

extremely important or urgent
極重要的；緊急的；迫切的
[ 詞或詞組後麪接一個that從句 ] The president said it was imperative that the release of all hostages be secured . 縂統說儅前要務是確保所有人質都獲釋。
[ 動詞後麪接一個帶to的不定式 ] It's imperative to act now before the problem gets really serious . 必須現在就採取行動，而不是等到問題變得難以收拾。

imperative adjective (GRAMMAR)

language   specialized
used to describe the form of a verb that is usually used for giving orders
祈使語氣
In the phrase "Leave him alone !", the verb "leave " is in the imperative form . 在句子 Leave him alone! 中，動詞 leave 用的是祈使語氣。 返回 imperative