这些词组都可以互换,都要用倒装,如: Hardly had he left home when it began to snow.他刚出门,雪就开始下了. as soon as 一...就... 这个词组不能用倒装,如: As soon as he left home,it began to snow.
hardly...when...表示“一……就” scancely/hardly...when/before和no sooner...than(都是一...就的意思)句型要注意倒装 如"He has no sooner understood than he reads"变成 No sooner has he understood than he reads.