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问题 单项选择题

磁盘存储器中，______是指沿磁盘半径方向单位长度所包含的磁道数，它与磁头的铁心厚度、定位精度有关。

A) 记录密度
B) 位密度
C) 存储容量
D) 磁道密度

答案

参考答案：D

解析： 磁盘表面由外向里分成若干个同心圆，每个圆称为一个磁道，每个单碟分布有1000个以上的磁道。磁道密度是指沿磁盘半径方向单位长度所包含的磁道数，它与磁头的铁心厚度、定位精度有关。

填空题

Part of the debate about culture revolves around issues of perspective and ownership. Within a nation such (1) the United States—a nation whose cultural heritage includes elements from every corner of the world (2) are a great many perspectives coexisting and intertwining in the cultural fabriC．When we all ask (3) as individuals, "what belongs to me, to my culture " we are rewarded with a spectacular variety of (4) ; in this way, different perspectives and ownership of different cultural traditions enriches everyone. But when we ask " (5) belongs to us, to our culture " we ask a much harder question. Do the people of the (6) States, or of any culturally complex human society, necessarily share common cultural elements If so, who gets (7) decide what those elements are
This debate is a crucial one in many cultures throughout the world (8) . In the US, the debate promises to impact the way we educate our children—that is, (9) manner and shape in which culture reproduces itself—and the way we write our laws. In (10) countries, equally crucial issues are at stake.
For many people, what is at stake is the character (11) US national identity. Hirsch argues that this identity needs to become less culturally fragmented; others, like Walker, (12) that the national character gets its strength from cultural diversity, from the freedom (at home and in (13) ) to celebrate, honor, and reproduce different cultural traditions. Those who take this latter view follow the reasoning (14) Shweder, arguing that we need to accept that there are multiple valid cultural perspectives and that two (15) perspectives can both be valid even though they might contradict one another.
Recognize that the position you (16) in this debate about culture—whatever position you take—is a political one with implications (17) what we should value, what we should praise, what we should accept, what we should teach. When (18) reflect on this debate, when you contribute your own voice to the discussion, try to be (19) of the implications that follow from your position. When you listen to the voices of others, try to (20) with awareness, deciding for yourself what is at stake and how their positions relate to your own.
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单项选择题

一般情况下，（）不会引起烟苗发黄。

A．缺氮

B．缺磷。

C．缺水

D．光照不足
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