He asked a lot of questions, and none of ______ was easy to answer.
| A．them | B．which | C．what | D．that |
How long do you think it will be ________ the computer company puts forward a new product?
| A．before | B．since | C．until | D．that |
The famous scientist, _______ a dinner party will be held tonight,is to arrive soon.
| A．in honour of him | B．in his honour | C．in whose honour | D．in which honour |
__________twice a year, whether it is a car or bus or a truck, is the rule that every driver must obey in this city.
| A．Examining | B．Examined | C．Being examined | D．Having been examined |
--- An ant has two stomachs --- one for itself, one for others.
--- Really? Quite interesting. I ____ anything about it.
| A．don’t know | B．have known | C．haven’t known | D．didn’t know |
AIDS is said__________the biggest health challenge to both men and women in that area over the past few years.
| A．that it is | B．to be | C．that it has been | D．to have been |