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问题 选择题

四边形ABCD的对角线相交于点O且OA=OB=OC=OD，则这个四边形（　　）

A．仅是轴对称图形

B．既不是轴对称图形，又不是中心对称图形

C．仅是中心对称图形

D．既是轴对称图形，又是中心对称图形

答案

如图所示：

∵四边形ABCD的对角线相交于点O且OA=OB=OC=OD，

∴OA=OC，OB=OD；AC=OA+OC=OB+OD=BD，

∴四边形ABCD是矩形，

∴四边形ABCD既是轴对称图形，又是中心对称图形．

故选D．

单项选择题

The nobler and more perfect a thing is, the later and slower it is becoming mature. A man reaches the mature (1) of his reasoning powers and mental faculties (2) before the age of twenty-eight; a woman at eighteen. And then, too, in the case of woman, it is the only reason of a sort--very mean in its (3) . That is why women remain children their whole life long; never seeing (4) but what is quite close to them, (5) fast to the present moment, taking appearance for (6) , and preferring (7) to matters of the first importance. For it is (8) his reasoning faculty that man does not live in the present only, (9) the brute, but looks about him and considers the past and the future; and this is the origin of (10) , as well as that of care and anxiety which so many people (11) Both the advantages and the disadvantages, which this (12) , are (13) in by the woman to a smaller extent because of her weaker power of reasoning. She may, in fact, be described as intellectually shortsighted, (14) , while she has an immediate understanding of what lies quite close to her, her field of (15) is narrow and does not reach to what is (16) ; so that things which are absent, or past, or to come, have much less effect upon women than upon men. This is the reason why women are inclined to be (17) and sometimes carry their desire to a (18) that borders upon madness. In their hearts, women think it is men’s business to earn money and theirs to spend it--if possible during their husband’s life, (19) , at any rate, after his death. The very fact that their husband hands them (20) his earnings for purposes of housekeeping strengthens them in this belief.

16（）

A.obscure

B.invisible

C.remote

D.primitive
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单项选择题

定置管理的理论依据有环境对人具有约束力的理论、满足人们生理和心理需求的理论和（）

A.灰色系统理论

B.系统动力学

C.系统工程

D.风险理论
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