Hardly.,when.No sooner.,than.

两者里面的hardly,No sooner如果放在句首,都必须用倒装.但是时态要对.这是典型的过去完成时的句子.
1）Hardly...when
--Hardly had I got into the room when it began to rain.
--正语序：I had hardly got into the room when it began to rain.
2) Nosooner ...than
--No sooner had I got into the room than it began to rain.
--I had no sooner got into the room than it began to rain.
先发生的用过去完成时,后发生的用过去是.

都必须倒装，但不必用完成时，过去时也可以的。