主病脏气衰微，或疼痛、惊恐、跌打损伤等病证的脉象是（）。

A.涩脉

B.结脉

C.代脉

D.促脉

E.牢脉

He failed in finding the job. I think that he _____to get some

more qualifications before applying for the job.

A．should have tried

B．must have tried

C．might have tried

D．needn’t have tried