The scientist does not study nature ________ it is useful to do so. He studies it because he takes pleasure in it.
| A．until | B．though |
| C．because | D．Unless |
China has a growing number of middle-class parents who _____ for years to get their only child into a top school．
| A．had been saved | B．have saved |
| C．had saved | D．have been saved |
Used to TV shows, _____ everything is quick and entertaining, many people do not have the patience to read a book that requires thinking．
| A．which | B．what | C．where | D．when |
Sitting cross-legged in a manner in which the bottom of a foot ______ toward an Arab is a serious insult．
| A．had pointed | B．pointed | C．have pointed | D．is pointing |
Coughing _____ also be used for social reasons, such as the coughing before giving a speech．
| A．may | B．should | C．must | D．need |
Production of less expensive car brands like Chery and BYD means more Chinese can ______ cars．
| A．recover | B．afford | C．maintain | D．produce |