The roof fell ____ he had time to rush out.
| A．until | B．before | C．when | D．Since |
Children in that kindergarten are sometimes asked to sit on their hands __________ listening to the teacher.
| A．while | B．though |
| C．after | D．during |
-What about the result of your final examination?
-Not so bad. Not so good as my parents expected，__________.
| A．either | B．instead |
| C．though | D．too |
__________ the Internet is of great help, I don't think it's a good idea to spend too much time on it.
| A．If | B．While |
| C．Because | D．As |
I was working as a waiter last month，__________ my friends were lying on the beach.
| A．whenever | B．though |
| C．for | D．while |
-When did the computer crash?
-This morning, while I __________ the reading materials downloaded from some websites.
| A．have sorted | B．was sorting |
| C．am sorting | D．had sorted |