——This wall of air is an effective answer to the problem and it ____ work.
——But it is a question to put such a wall of air around the statue.
| A．may | B．must | C．should | D．could |
【原创】Nobody noticed the thief slip into the house because the lights happened to__________.
| A．put up | B．give in |
| C．be turned on | D．go out |
【原创】I don't remember___________ to the airport that year.
| A．to be taken | B．being taken |
| C．having | D．to take |
【原创】A man does not know the difficulty of anything_________ he does it personally.
| A．although | B．if | C．because | D．unless |
【原创】There is a _________ of 1000 dollars for the return
| A．reward | B．prize |
| C．thank | D．praise |
【原创】Isn't it very kind __________ your parents to do that for us?
A. for B to C. about D. of