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 |
You can find me easily, for there is only one house _______ roof is flat.
| A．whose | B．of which | C．of that | D．that |
I shall never forget the days ______ I stayed in Africa, ________ has brought me a lot of advantages.
| A．that; which | B．when; which | C．when; that | D．which; that |
Never before in my life ________such a beautiful girl with so many high qualities.
| A．I met | B．did I meet | C．I have met | D．have I met |
—— Don’t smoke today, honey, it’s three months since you smoked.
—— OK, I ______.
| A．do | B．don’t | C．will | D．won’t |
________ the mountains was hard work for them but as they looked around, they could not help screaming.
| A．Climb | B．To climb | C．For climbing | D．They climbed |