Beijing was under an “orange” smog alert on Feb. 24, which marks the first time the second-highest warning level of a new system introduced last year_______.
| A．has been raised | B．raised |
| C．has risen | D．rose |
The painting is .so valuable that it is difficult to calculate____ its price would be.
A that
B. which
C．what
D.＼
It doesn't matter ____ you turn right or left at the crossing—both roads lead to the park.(2012•天津）
| A．whether |
| B．how |
| C．if |
| D．when |
____ you don’t like him is none of my business.
| A．What |
| B．If |
| C．That |
| D．Whether |
It is obvious to the students____ they should get well prepared for their future (2009•天津）
| A．as |
| B．which |
| C．whether |
| D．that |
--- Is there any possibility____ you could pick me up at the airport?
--- No problem（2009 .浙江）
| A．when |
| B．that |
| C．whether |
| D．what |