回答数
4
浏览数
104
、人生海海
We need be vigilant before dangers occur. There is no longer use for us to be vigilant once they occur.
CallmeNicole
Be on guard be careful
多妈elva
原用法是对的, of不能删."of + 名词" 很多可以等价于形容词, 做表语, 是正式用语. 比如It is of help. = It is helpful.
巧儿妹妹
*be on the alert*heighten one's vigilance
优质英语培训问答知识库
