They have waited here for half an hour的同义句

问题描述:

They have waited here for half an hour的同义句

It is five years since they waited here.
It has been five years since they waited here.They have waited here for half an hour.(改为同义句)They have waited here_______half an hour_________.They have waited here for half an hour.(改为同义句)They have waited here since half an hour ago .