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问题 选择题

下列各物质中，能使酸性KMnO4溶液褪色的物质有(          )

A．甲烷

B．甲苯

C．乙烯

D．苯

答案

BC

高锰酸钾具有强氧化性；能使其褪色的具有还原性。甲苯能氧化成苯甲酸，乙烯能氧化成二氧化碳。

问答题 简答题

说出脉序的分类、特点，并举例。
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单项选择题

One of the main responsibilities of ICMP is to report （1）. Although technology has produced increasingly reliable transmission media, errors still exist and must be handled. IP is an （2）protocol. This means that error checking and error control are not a concem ofIP JCMP wasdesigned, in part, to compensate for this shortcoming. Howerver, ICMP does not （3）errors, itsimply reports them. Error correction is left to the higher-level protocols. Error messages arealways sent to the original（4） because the only information available in the datagram aboutthe route is the source and destination 1P addresses. ICMP uses the source IP address to send theerror massage to the source of the （5）

（2）是（）

A.reliable

B.unreliable

C.available

D.Unavailable
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