(单选题)21: ____ is big and round in the sky today. A: moon B: The moon C: Moon D: Star ...

(单选题)15: The water gives up energy and becomes cooler____________the ice receives energy and melts. A: when B: while C: for D: because ...

(单选题)9: Economics, several courses of which I have taken thus far, ____________to be difficult but useful for almost all students. A: prove B: proves C: have been proved D: are proved ...

(单选题)35: I'd like to __________ him to you for the job. He is a very clever and industrious boy. A: refer B: suggest C: recommend D: propose ...

(单选题)13: The conductor and composer ____________by a crowd of people. A: are greeted B: is greeted C: greets D: have been greeted ...

(单选题)21: Cattle____________to graze on the village common. A: are allowed B: is allowed C: allows D: allow ...

(单选题)9: Large quantities of water ____________cooling purposes. A: are needed for B: is needed to C: are need to D: is need for ...

(单选题)35: It ____________ whether he will go on with his study at the university. D: doesn't decide ...

(单选题)5: “No, no”, he whispered, ______ talking to himself. A: while B: even if C: as if D: when ...

(单选题)19: 关于复球面，下列说法正确的是（） A: 复球面与复平面一一对应 B: 复球面与扩充复平面一一对应 C: 无穷远点是存在的 D: 无穷远点就是在无穷远处的一个点 ...