【2015·江苏】The number of smokers, _____ is reported, has dropped by 17 percent in just one year.
| A．it | B．which | C．what | D．as |
So sudden ________that the residents had no time to escape.
| A．was the earthquake | B．did the earthquake |
| C．the earthquake did | D．the earthquake was |
— How long will it be _______ the president pays another visit to China?
— It all depends.
| A．before | B．until | C．since | D．when |
Look! the ground is wet. It must have rained last night, _______?
| A．hasn’t it | B．didn’t it | C．mustn’t it | D．hadn’t it |
Generally speaking, _______ according to the directions, the drug has no side effect.
| A．if taking | B．if taken | C．if to take | D．if being taken |
Tom is _______ learning English. To learn it well, he abandons all his hobbies.
| A．bound to | B．desperate to | C．bent on | D．accustomed to |