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问题 选择题
计算(
7-x
)2+
(x-9)2
的结果是（　　）
A．-2B．16-2xC．2x-16D．2
答案

∵要使

7-x
有意义，

∴7-x≥0，

∴x≤7，

∴(

7-x
)2+
(x-9)2
=7-x+9-x=16-2x，

故选B．

单项选择题

Anthropologists assert that cultures advance only when independence replaces dependence—that is, only when imposition by outsiders is replaced by initiative from within. In other words, the natives of a culture are the only ones who can move that culture forward. Non-natives may provide valuable advice, but any imposition of their views threatens independence and thus progress. If one looks at individual schools as separate cultures, therefore, the key to educational progress is obvious that ______.
Which one of the following best completes the passage

A．individual schools must be independent of outside imposition

B．some schools require more independence than others, depending on the initiative of their staffs and students

C．school system officials must tailor their initiatives for change to each individual school in the system

D．outsiders must be prevented from participation in schools’ efforts to advance

E．(E) the more independent a school is, the more educational progress it will make
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单项选择题 B型题

见于巨幼细胞性贫血（）

A.轻度皮肤黏膜出血伴骨髓增生低下，雄激素治疗有效

B.血小板数量减少伴巨核细胞成熟障碍

C.红系增生活跃，骨髓细胞外铁消失

D.维生素B12叶酸测定下降，骨穿示巨幼性改变

E.严重内脏出血伴三系血细胞下降，骨髓多部位增生极度低下，无巨幼细胞
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