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、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
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