---Hello may I speak to Millie please?-.A. Who are you?B. What are you?C. Im Millie.

问题补充：

---Hello, may I speak to Millie, please? ---.

A. Who are you?

B. What are you?

C. Im Millie.

D. This is Millie speaking.

答案：

A. Who are you?

B. What are you?

C. Im Millie.

(答案→)D. This is Millie speaking.

解析：在打电话是，指对方用that,指自己用this,故选D