. - The speaker is a tall man with glasses.

- Then it_____ be Mr. Smith, who is short and thin.

A．wouldn't

B．won't

C．mustn't

D．can't

汞毒作用的基础是（）

A.与红细胞结合

B.与血红蛋白结合

C.Hg-SH反应

D.与金属硫蛋白结合

E.与核酸结合