As we all know, regular exercise can be _____to health.
—Did you stay up late last night? —Not very late. It was half past elevenI went to bed.
—When didaccident happen? —Oh, it was onSunday towards the end of this summer, as far as I can remember.
The project is so designed that once _______ nothing can be done to change it.
There was a man crying over there.He _______ himself.
______ a good result,the professor decided to do the experiment once more.