题目内容：

You can,__the ske is clear,see as far as the old temple on top the mountain,but not today.
这为什么选when?

优质解答

这个是把状语提前了,做插入语.
正常语序you can see as far as the old temple on top the mountain when the sky is clear, but not today.
当天空清楚的时候,你能够尽可能远地看到处在山上的老庙,但不是今天.