Mark was a student at this university from 1999 to 2003, _____ he studied very hard and was made Chairman of the Students’ Union.
A during which time B for which time C during whose timeD by that time
I thought things would get better, but _____it is they are getting worse.
| A．before | B．because | C．as | D．after |
Although he knew little about the large amount of work done in the field , he succeeded ____other more well-informed experimenters failed.
| A．as | B．unless | C．what | D．where |
John waited at the bus-stop for nearly half an hour _____ the bus finally arrived .
| A．when | B．as | C．before | D．while |
Not that I’m unwilling to lend you a hand , ____I’m too busy for the moment .
| A．because | B．but that | C．but | D．however |
Jack had traveled six miles across the Channel _____his engine failed and was forced to land on the sea .
| A．when | B．until | C．after | D．since |