单项选择题
The survival of civilization, as we know, is（）threat.
A.with inB.underC.to wardsD.upon
单项选择题 The wise man exercises（）in his behavior and enjoyments.
单项选择题 The police will give you a ticket if you（）the speed limit.
单项选择题 I guess the whole paper has to be rewritten; only the first few paragraphs may be（）
