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单项选择题

下列截面形状的风管和材质、过流断面积和通过风管的风量均相同，哪个风管单位长度的气流阻力最大？( )

A.
B.
C.
D.
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单项选择题
　Some villagers were going to celebrate an important wine festival（酒宴）in a few days' time, so they borrowed a huge barrel from the nearest town, put it in the village square; and decided that each of them should empty a bottle of the best wine he had into it, so that there should be plenty at the feast（宴会）.
One of the villagers thought he would be very clever. "If I pour a bottle of water in, instead of wine, no one will notice it," he said to himself, " because there will be so much excellent wine in the barrel that the water will be lost in it. "
The night of the feast arrived. Everybody gathered in the village square with their bowls and their glasses for the wine. The tap（塞子）on the barrel was opened, but what came out was pure water. Everyone in the village had the same idea．
Where would the feast be held according to the passage?（　　
A.Intheirhouses
B.Inthenearesttown
C.Aroundthebarrel
D.Inthevillagesquare
单项选择题
　Some villagers were going to celebrate an important wine festival（酒宴）in a few days' time, so they borrowed a huge barrel from the nearest town, put it in the village square; and decided that each of them should empty a bottle of the best wine he had into it, so that there should be plenty at the feast（宴会）.
One of the villagers thought he would be very clever. "If I pour a bottle of water in, instead of wine, no one will notice it," he said to himself, " because there will be so much excellent wine in the barrel that the water will be lost in it. "
The night of the feast arrived. Everybody gathered in the village square with their bowls and their glasses for the wine. The tap（塞子）on the barrel was opened, but what came out was pure water. Everyone in the village had the same idea．
What is the huge barrel used for?（　　
A.Holdwater
B.Holdwine
C.Taketheplaceofwinebottle
D.Emptybottles
单项选择题
采集粪便培养标本，不正确的做法是（）A.嘱患者排便于消毒便盆内B.取带脓血或黏液的粪便2～5g于无菌容器内C.立即送检D.无便意时可通过灌肠采集粪便E.留取粪便前先嘱患者排尿
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