If the United States had built more homes for poor people in 1955,the housing problems now in some parts of this country ________ so serious.
A. wouldn't be
B. will not have been
C. wouldn't have been
D. would have not been
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后张预应力混凝土梁、板在孔道压浆后移运的,其压浆浆体强度应不低于设计强度的()。
A. 60%
B. 70%
C. 75%
D. 80%
社会学家关于人类行为的基本假设,人类行为由()所塑造。
芳香第一胺的鉴别反应又称为
A. 重氮化反应
B. 重氮-偶合反应
C. 呈色反应
D. 缩合反应
E. 配位呈色反应