--Do you know the girlis talking to your teacher?---She is my new classmate Sarah.A. whoB.

问题补充：

--Do you know the girlis talking to your teacher?

---She is my new classmate Sarah.

A. who

B. whom

C. which

D. whose

答案：

(答案→)A. who

B. whom

C. which

D. whose

解析：句意：——和你的老师讲话的女孩是谁？——她是我的同学莎拉。whom 只能在从句作宾语；which 指的是物，不能指人；whose 指某人的或某物的；who作为定语从句的连接词，既在从句中作主语，又要代指人。因此选A。