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问题 选择题

下图所示是分离混合物时常用的仪器，从左至右，可以进行的混合物分离操作分别是

[ ]

A．蒸馏、蒸发、萃取、过滤

B．蒸馏、过滤、萃取、蒸发

C．萃取、过滤、蒸馏、蒸发

D．过滤、蒸发、萃取、蒸馏

答案

答案：B

单项选择题

Remote administration types are an example of one kind of (71) malicious software, the Trojan horse, or more simply Trojan. The purpose of these programs isn’t replication, (72) to penetrate and control. That masquerade as one thing when in fact they are something else, usually something destructive. There are a number of kinds of Trojans, including spybots, (73) report on the Web sites a computer user visits, and keybots or keyloggers, which record and report the user’s keystrokes in order to discover passwords and other confidential information.

RATS attempt to give a remote intruder administrative control of an infected computer. They work as (74) pairs. The server resides on the infected machine, while the client resides elsewhere, across the network, where it’s available to a remote intruder. Using standard TCP/IP or UDP protocols, the client sends instructions to the server. The server does (75) it’s told to do on the infected computer.

（73）处填（）。

A．that

B．which

C．where

D．whit which
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填空题

已知某大平壁的厚度为10mm，材料导热系数为45W/（m•K），则通过该平壁单位导热面积的导热热阻为（）。
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