Hardly had I got out of the house when it beign to rain.倒装句

题目

Hardly had I got out of the house when it beign to rain.倒装句
其中had怎么用?用 was 两者有什么区别?

答案

这是一个固定句式：
Hardly had sb.done sth.when...刚刚...就...
还有一个类似的句式：
No sooner had sb.done sth.than...刚刚..就...