be about to do:
1) 表示即将发生的动作,在时间上指最近的将来。如:
We are about to start. 我们就要出发了。
The new school year is about to begin. 新学年开学在即。
2) 在含有be about to do的句子中,不能再加时间状语。如:
Wrong: The medical team is about to start immediately.
Right: The medical team is about to start. 医疗队就要出发了。
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一般说来,“be to do” 这个结构有两种语法意义,其一是连系动词be+动词不定式做表语,其二是be to是一个独立词汇单位,具有情态含义,可以把它叫做情态习语(modal idiom)。
一、be +动词不定式, 不定式做表语,表示主语和表语在概念上是等同的。如:
The problem is to find a solution.
His plan is to clean the room.
My wish is to be a doctor.