3We were about to climb up to the top of the mountain ________ it began to rWe were about to climb up to the top of the mountain_______ it began to rain heavily.A. as B.while C.when D.since
问题描述：
3We were about to climb up to the top of the mountain ________ it began to r
We were about to climb up to the top of the mountain_______ it began to rain heavily.
A. as B.while C.when D.since
答
C(原因的话..楼主原来准备选哪个？
答
C.when 为正确选项。
这是一个固定句式be about to do sth when ...“正要做某事，这时（突然）。。。”的意思。
如：Tom was about to leave when the phone rang.汤姆正要离开，这是电话响了。
【俊狼猎英】团队
答
C be about to...when...
答
选C。
翻译为：我们正要爬向山顶，突然下起了大雨。
when 放在句中，常常表示“突然”。
又如：
I was doing my homework when the light went out。我正在做作业，突然灯灭了。
而as表示“当...", 常常放在句首。
be about to do sth when....在英语中这是一个固定表达方式.
即当一个动作就要发生时另一个动作发生了.
when这里是一个并列连词,相当于,and at the same time.
所以这是一个并列句.不是复合句。