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问题 填空题

生活垃圾一般分为三类：

__________垃圾，如___________等；　　　

__________垃圾，如___________等；　　　

__________垃圾，如___________等。　　　　

答案

可回收垃圾，如废纸等；不可回收垃圾，如果皮等；危险有害垃圾，如废电池等

单项选择题

The usual way to ensure reliable delivery is to provide the (71) with some feedback about what is happening at the other end of the line. Typically, the protocol calls for the receiver to send back special (72) flame bearing positive or negative (73) about the incoming frames. If the sender receives a positive acknowledgement about a frame, it knows the frame has arrived safely. On the other hand, a negative acknowledgement means that’ something has gone wrong, and the frame must be transmitted again.

An additional complication comes from the possibility that hardware troubles may cause a flame to (74) completely. In this case, the receiver will not react at all, since it has no any reason to react. It should be clear that a protocol in which the sender transmits a frame and then waits for an acknowledgement, positive or negative, will hang forever if a frame is ever lost due to, for example, (75) hardware.

（73）处应填（）。

A．application

B．connection

C．stream

D．acknowledgement
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单项选择题

某机电公司承接某化工厂的设备安装工程。设备安装需用起重机吊装就位，吊装施工前，机电公司按照工程需要，认真选择钢丝绳、滑轮组和卷扬机。滑轮组选用H系列滑轮组，滑轮组跑绳选用安全系数适合的钢丝绳，并对卷扬机进行容绳量校核。所有吊具选用完毕后，进行吊装工作。

对正确使用滑轮组时需考虑的因素的叙述，错误的说法是( )。

A．滑轮组的穿绕方法

B．滑轮组轮槽与钢丝绳直径匹配

C．滑轮组的最长极限距离

D．钢丝绳在滑轮组中的偏角
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