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问题 填空题

如图所示，甲、乙两滑轮组吊着同样重的物体，若不考虑滑轮、绳子的重力与摩擦力．则当两个滑轮组都静止不动时，F1：F2=______，若F1=500N，F2=400N时，分别使吊着的物体都升高h米，则这两个滑轮组的机械效率之比是______．

答案

（1）由图可知，滑轮组甲中n=2，滑轮组乙中n=3，

∵不考虑滑轮本身受到的重力和摩擦力，

∴F1=

1
2
G，

F2=

1
3
G，

∴F1：F2=

1
2
G：
1
3
G=3：2；

（2）η1=

Gh
F1×2h
×100%

η2=

Gh
F2×3h
×100%

则η1：η2=

Gh
F1×2h
×100%：
Gh
F2×3h
×100%=
Gh
500N×2h
：
Gh
400N×3h
=1200：1000=6：5．

故答案为：3：2；6：5．

单项选择题

咳嗽肺阴亏耗证，痰的特点是：（）

A.痰中带血、质浊、有腥臭味

B.痰多、色黄、质稠

C.痰白、质稀

D.脓血相兼浊痰、有腥臭味

E.痰少、质粘、夹有血丝
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单项选择题

Randy Kraus was paralyzed. His left side was useless. But his right hand was (1) enough to lift a bucket to his forehead. Once, he’d been a police officer and owned a private-eye agency. Once, he’d been p and able. Now, he felt he was nothing.
His (2) started with Parkinson’s disease, but it didn’t (3) there. In July 2002, the 60 year old Kraus went into the hospital for an operation to control the shaking. (4) , during the operation, he had a stroke. He was paralyzed. The (5) man, who loved golf, could think, but couldn’t (6) . Kraus wanted the doctors to (7) it to him straight. "You may never walk again, " they told him. "Maybe you won’t (8) be able to talk. "
Once at home, he (9) he couldn’t lift a fork or take a drink by himself. Physical treatment was so painful and slow. What did he have to (10) for So now Kraus held the gun against his head. (11) the cold metal on his skin, he began to consider not his pain, but the pain he (12) cause his wife, daughters and grandchildren. He didn’t pull the trigger.
"You are where you are", his exercise physiologist, Andrew Garud told him. "The pace would be slow; the pain would be (13) . But as long as you are (14) , you have the ability to get better. " After three months of (15) with Garud, Kraus wanted to see if he could (16) . He could. Then he took three steps, sat down and cried like a baby. One step (17) to another. Next he managed a short walk. It was the hardest (18) of Kraus’s life.
Garud kept saying he could (19) more. Now, Kraus can brush his teeth, shave himself and get around the house with a walker. Little success only the paralyzed can (20) understand.

A．safe
B．good
C．big
D．free
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