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问题 选择题

下列说法：①5个有理数相乘，当负因数个数为3个时，积为负；②-1乘以任何有理数，都等于这个有理数的相反数；③两个有理数的积为负数，则这两个有理数都为负数；④绝对值大于1的两个数相乘，积比这两个数都大，其中正确的有[ ]

A．1个

B．2个

C．3个

D．4个

答案

答案：A

选择题

图中①②③三个图分别代表某个概念或某类物质。以下各项中，能构成图中关系的是：

[ ]

A．DNA、染色体、基因

B．物种、群落、种群

C．酶、蛋白质、激素

D．减数分裂、有丝分裂、无丝分裂
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单项选择题

(1) In the strength of the carrier signal is varied to represent binary 1 or 0.

(2) is a system that can map a name to an address and conversely an address to an name.

(3) is a three-way handshaking authentication protocol that it’s packets are encapsulated in the point-to-point protocol

(4) is an approach that enables an ATM Switch to behave like a LAN switch.

(5) is an guided media which is made of glass or plastic and transmits signals in the form of light.

3（）

A．PPP

B．PAP

C．CHAP

D．LCP
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