流体在直管中流动，当Re（）4000时，流体的流动类型属于湍流。
A.＜；
B.≥；
C.≤；
D.≠。
参考答案：B
At this moment in different places of the world people are doing different things. In Beijing it's early morning. People are sleeping.
In London people are leaving work to go home. They are waiting for buses or running for trains. Some people are driving their cars. Some are having afternoon tea at home or walking to the pubs(酒吧) to have a drink.
In Moscow(莫斯科) it's evening and people are having supper at home or in restaurants. Some are going to watch a ballet(芭蕾舞). Some are drinking in the pubs.
In Los Angeles(洛杉矶) it's morning. People are working in their offices. Children are starting their lessons.
New York is midday now. People aren't working but having lunch. They are eating hamburgers or hot dogs and drinking coffee or Coke. Some people are seeing friends or shopping.
小题1:When children in Los Angeles are starting their lessons, people in Beijing
are
A．playing basketball
B．seeing films
C．having lessons
D．sleeping小题2:From the passage, we can see the time in New York now is .
A．6∶00
B．9∶00
C．10∶00
D．12∶00小题3:When the time in London is 6:00 p.m., it’s in Moscow.
A．8:00 p.m.
B．9:00 p.m.
C．8:00 a.m.
D．9:00 a.m.
就显效和维持时间而言，拮抗肌松药的最佳组合是()
A．依酚氯铵和胃长宁
B．依酚氯铵和阿托品
C．新斯的明和阿托品
D．吡啶斯的明和阿托品
E．以上均否
At this moment in different places of the world people are doing different things. In Beijing it's early morning. People are sleeping.
In London people are leaving work to go home. They are waiting for buses or running for trains. Some people are driving their cars. Some are having afternoon tea at home or walking to the pubs(酒吧) to have a drink.
In Moscow(莫斯科) it's evening and people are having supper at home or in restaurants. Some are going to watch a ballet(芭蕾舞). Some are drinking in the pubs.
In Los Angeles(洛杉矶) it's morning. People are working in their offices. Children are starting their lessons.
New York is midday now. People aren't working but having lunch. They are eating hamburgers or hot dogs and drinking coffee or Coke. Some people are seeing friends or shopping.