-----I stayed up late last night preparing the speech.
----- you look so tired today.
A. No doubt
B. No problem
C. No time
D. No wonder
网友回答
A. No doubt
B. No problem
C. No time
(答案→)D. No wonder
解析：考查交际用语。A毫无疑问；B没有问题；C一会公夫；D难怪；句意：—昨天晚上我熬夜准备演讲。—难怪今天你看上去很疲惫。根据句意说明D正确。