酸雨是指因()污染而造成的酸性降水,请从下列选项中选出。
A.土壌
B.空气
C.海水
D.植物
参考答案:B
华支睾吸虫的发育过程需要2个中间宿主,其第一中间宿主是()
A.淡水螺
B.淡水虾
C.钉螺
D.土蜗螺
E.扁卷螺
It’s better to teach the people out of work means to earn money( ) to provide money for them.
A.than
B.as
C.most
D.more