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问题 单项选择题

维生素D缺乏性手足搐搦症以“喉痉挛”为突出症状的小儿年龄多在()

A．1个月以内

B．6个月以内

C．6～12个月

D．1～2岁

E．2岁以上

答案

参考答案：B

解析： 喉痉挛多见于6个月以下的婴儿，因喉部肌肉及声门突然发生痉挛，表现为吸气性呼吸困难、声嘶、犬吠样咳嗽、喉鸣等。少数可突然发生窒息而死亡。

名词解释

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单项选择题

In low-speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high-speed networks, this approach often works poorly, because in the ______ between sending the notification and notification arriving at the source, thousands of additional ______ may arrive. In ATM network, a major tool for preventing ______ is ______ control. When a host wants a new virtual ______, it must describe the traffic to be offered and the service expected.

A．interval
B．time
C．slot
D．delay
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