下列哪一顼不是格林-巴利综合征经典表现A．四肢弛缓性瘫痪 B．四肢运动障碍重于感觉障

One ofthe main resposibilities ofICMP is to report  （） . Although technology hasproduced increasingly relaible transmission media, errors still exist and must be handled. IP isan  （）  protocol. This means that error checking and error control are not a concem ofIP. ICMP was designed, in part, to compensate for this shortcoming. Howerver, ICMP doesnot  （） errors, it simply report them. Error correction is left to the higher-levelpotocols. Error messages are always sent to the original  （）  because the only informationavailable in the datagram about the route is the source and destination IP addresses. ICMP usethe source IP address to sent the error massage to the source ofthe（）.

ICMP usethe source IP address to sent the error massage to the source ofthe（）.

A．datagram

B．frame

C．service

D．protocol

如图所示，单摆甲放在空气中，周期为T_甲；单摆乙放在以加速度a向下加速运动的电梯中，周期为T_乙；单摆丙带正电，放在匀强磁场

B中，周期为T_丙；单摆丁带正电，放在匀强电场居中，周期为T_丁，那么（　　）

A．T_甲＞T_乙＞T_丙＞T_丁

B．T_乙＞T_甲=T_丙＞T_丁

C．T_丙＞T_甲＞T_丁＞T_乙

D．T_丁＞T_甲=T_丙＞T_乙

具有保护和引诱昆虫传粉等作用的是（）。

A.花梗

B.花托

C.花被

D.雄蕊

E.雌蕊

A．到这儿来了才知道比日本大多了
B．以为和日本一样大
C．来中国以前我一点儿也不了解中国

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