We were swimming in the lake___suddenly the storm started.

问题描述:

We were swimming in the lake___suddenly the storm started.
填before为什么不行?在风暴突然开始之前我们一直在游泳

用when,因为这句表达的意思是下暴雨时我们还在游泳.
要用before的话前半句时态要改成We had been swimming in the lake,然后suddenly也要去掉,整句就要是We had been swimming in the lake before the storm started.这样才能表示时间上的先后.