31. The decision ______ Internet addiction（成瘾）as a mental disorder has caused much debate.
| A．to classify | B．classifying |
| C．being classified | D．to be classified |
Only then _____ how much damage had been caused.
| A．she realized | B．She had realized |
| C．had she realized | D．did she realize |
As we all know，dark glasses can ________ the eyes from strong sunlight.
| A．prevent | B．care | C．help | D．protect |
How the big forest fire has remains to be a mystery.
| A．turned up | B．broken out | C．taken place | D．broken up |
It was on October 1st _____ new China was founded.
| A．which | B．that | C．when | D．as |
I would rather _____ the weekend at home than ______ all the way to such a place.
| A．spending, driving | B．spend, to drive | C．spend, drive | D．to spend, drive |