单选题 In our own galaxy, the Milky Way, there are perhaps 200 billion stars, a small part of them probably have planets on which life is feasible.
A. a small fraction in which B. a small fraction of which
C. a small fraction which D. which a fraction of

【正确答案】 B
【答案解析】[解析] 本题考查结构应用。英语的定语从句(不论是限定性或非限定性)中，当关系代词作介词宾语时，介词前置，其中whom指人，which指物。而介词of表示整体中的一部分，a fraction of表示“……的一部分”，所以B为答案。