50．He worked at a research center whose work _____ patience and carefulness.

　 　　 A．cared about 　　　　　 B．called for　 　　　　　 C．stood for　　 　　　 D．led to

49．There are two rooms in the house, _____ serves as a kitchen.

　　 A．the smaller of which　 　　　　　　　　　　　　　 B．the small of which　

　　 C．the smaller of them　　 　　　　　　　　　　　　 D．the smaller one

48．In order to keep healthy, she has to go on _____.

　 　 A．food　　　 　　　　　　 B．diet　　　 　　　　　 C．a diet　　　 　　　　　 D．a food

47．With the flood drawing near, all the buildings around are _____.

　　 A．dangerous 　　B．in danger 　　　　　 C．in the danger　 D．at danger

46．The students ­­______ use cell phones while they are at school.

　 　　 A．dare not　　 　　　 B．not dare　　 　　　 C．dare not to　　 D．dared not

45．Your speech is quite good _______ a few mistakes in pronunciation.

　 　　 A．except for　　 　　 B．except　 　　　　　　　 C．but　 　　　　　　　　　　 D．besides

44．Some students have trouble ___ grammar while others have difficulty ___ new words．

　 　　 A．in; remember　 　　　　　　　　　　　　　　　　　　　　　　　 B．for; to remember　

　　　　 C．on; remembering　 　　　　　　　　　　　　　　　　　　　 D．with; remembering

43．---I’d love to go with you to the concert, but I’m short of money these days.

　 　 ---That’s all right．____.

　 　　 A．We are friends, and we should help each other　

　　　　 B．It will be my treat

　 　　 C．You know I have a lot of money　　　　　　　

　　　　 D．I’ve got enough money