水俣病的发病原因是（）
A.慢性砷中毒
B.慢性镉中毒
C.慢性铅中毒
D.慢性硒中毒
E.慢性汞中毒
参考答案：E
Just a few months before the examination the lazy bone studied day and night _____ that he
should fail. [ ]
A. in case
B. so long as
C. for fear
D. on condition
对头发稀少的人，挑烫可以使头发蓬松，（）头发稀少的缺陷。
A.减少
B.弥补
C.补充
D.扩张
