—Why didn't Mr.Smith arrive on time for the meeting?
—He must have been ________ on his way here in the traffic jam.
| A．held up | B．put up |
| C．taken up | D．given up |
Air pollution is getting more and more serious, so we must take action ________ it is too late.
| A．before | B．after |
| C．until | D．when |
Sarah Brightman, ________ will fly to space in 2015, is the first woman to fly there in the field of music.
| A．who | B．that |
| C．which | D．whose |
The businessman wears a suit and a tie with a beard ________ the season.
| A．whatever | B．wherever |
| C．whenever | D．however |
The course about Chinese food attracts over 100 students per year, ________ up to half are from overseas.
| A．in which | B．for whom |
| C．with which | D．of whom |
—When choosing furniture, you only focus on function while I think more about the design.
—That's ________ we differ.
| A．how | B．what |
| C．which | D．where |