单选题
The large size and roughly circular shape of the Pacific made some scientists think that it ______ a hole left when the moon separated from the earth. A. used to be B. would have been C. might have been D. should have been
【正确答案】
C
【答案解析】根据句子的意思，it might have been a hole只是一种猜测，其他几个选项都不符合要表达的这种逻辑意义。题句意为：“太平洋浩瀚巨大，又大致呈圆形，这使得某些科学家认为它也许是月球脱离地球时留下的一个大坑。”