题目

The teacher is an enthusiastic woman _____ Ms Shen and her method of teaching is nothing like ___ of the teachers at my Junior High School. A. called; that       B. calling; that         C. is called; that        D. called; it  答案：A 解析: 略如图，墙上有两个钉子a和b，它们的连线与水平方向的夹角为45°，两者的高度差为l。一条不可伸长的轻质细绳一端固定于a点，另一端跨过光滑钉子b悬挂一质量为m1的重物。在绳子距a端的c点有一固定绳圈。若绳圈上悬挂质量为m2的钩码，平衡后绳的ac段正好水平，则重物和钩码的质量比为A．      B． 2      C．     D．