下列哪种有害金属经甲基化后毒性增加（）
A.镉
B.汞
C.铅
D.砷
E.氟
参考答案：B
--- Are you _____with doing a lot of homework everyday?
--- Sometimes I am. But as a student , we have to do so at present.
A．satisfied
B．encouraged
C．bored
D．pleased
大多数抗恶性肿瘤药物所共有的不良反应（）
A.脱发
B.骨髓抑制
C.心脏损害
D.胃肠道反应
E.肝、肾损害
