—I had been working till 4 a. m. to prepare a report for my boss.—you look very tired.A. N

问题补充：

—I had been working till 4 a. m. to prepare a report for my boss.

—you look very tired.

A. No doubt

B. No hurry

C. No wonder

D. No need

答案：

A. No doubt

B. No hurry

(答案→)C. No wonder

D. No need

解析：No doubt毫无疑问，No hurry不急，No wonder难怪，No need没有必要，句意：我一直工作到凌晨四点为我的老板准备了一份报告。难怪你看起来非常累。故选C。