. I just don't understand_____________ that prevents so many Americans from being as happy as one might expect.
| A．why it does | B．what it does |
| C．what it is | D．why it is |
It was quite dark, but I could see a man _____ on the floor ______up.
| A．lies ; tied | B．lying ; tied | C．lying ; ties | D．lie ; tied |
If you grow up in ______ large family, you are more likely to develop ______ ability to get on well with ________ others.
| A．/; an; the | B．a; the; / | C．the; an; the | D．a; the; the |
Children will work actively if _______.
| A．praise | B．praised | C．praising | D．to praise |
Before I realized that what I said at the meeting did hurt him, he _________ without a word.
| A．drove away | B．was driving away | C．was driven away | D．had driven away |
—I wonder why Suzan looks worried today.
—I’m not sure, but she ________a small accident driving here.
| A．could have | B．might have | C．might have had | D．must have had |