It took a great deal of courage to admit that all his efforts had been ____.
| A．in vain | B．in turn | C．in return | D．in danger |
The flu is believed _____by viruses that like to reproduce in the cells inside the human nose and throat.
| A．causing | B．being caused | C．to be caused | D．to have caused |
—How did you find the talk this morning?
—______.
| A．By asking my students | B．It was easy to find |
| C．Very disappointing | D．Just in time for it |
The flowers _________sweet in the botanic garden attract the visitors to the beauty of nature．
| A．to smell | B．smelling | C．smelt | D．to be smelt |
—You have made progress in your English study, haven’t you?
—Yes, but much ____.
A remains to do B is remained to do
C remains to be done D is remained to be done
There is no possibility ________ he will keep his word．He is always telling lies.
| A．how | B．whether | C．when | D．that |