臭氧层破坏的主危害是（） A.加速酸雨形成 B.有利于啮齿动物、昆虫生长繁殖 C.使
题型：单项选择题
问题：
臭氧层破坏的主危害是（）
A.加速酸雨形成
B.有利于啮齿动物、昆虫生长繁殖
C.使人类皮肤癌、白内障发病率增加
D.有利于植物生长
E.光敏感性皮肤病发病率增加
题型：单项选择题
短文改错。
Last night when Steven and I was having a walk in the street, we suddenly heard a painful cry for
help under a tree nearby. 
We quickly ran to the tree and found a boy laying on the ground with a stick
in his leg. He had fallen of the tree. Steven suggested we pulled the stick out at once, but I disagreed,
Because I had learned little about first aid at school. The stick in the leg would help controlling the
bleeding. As there was no telephone,we managed to find a taxi. We took the boy to the hospital. The
doctors examined the boy fast and we got to know where the boy lived. So we telephoned his parents
and left after he came to the hospital. We did a good deed.
的假设前提是：（）。