Mr. Smith gradually _____ a knowledge of the subject.
--- A high-tech exhibitionin the National Museum. --- Really? What about visiting it now? .
The middle-aged man over there, for life was oace very hard, is now a very successful businessman.
—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.