单选题 Tom ______ better than to ask Dick for help.
A. shall know B. has known
C. shouldn't know D. should have known

【正确答案】 D

【答案解析】[解析] know better than to do sth．=be wise enough not to do sth．懂得不该；非常精明不至于做(某种蠢事)。should have known better than to ask Dick for help应懂得不该向荻克寻求帮助。