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问题 选择题

如图是物体做直线运动的速度-时间图象，下列说法正确的是（　　）

A．从t=2s到t=4s 物体处于静止状态

B．从t=0s到t=2s 物体加速度的大小为1m/s2

C．从t=4s到t=6s物体做反方向的匀减速直线运动

D．从t=0s 到t=6s 物体的位移为零

答案

A、由图知，t=2s到t=4s内物体的速度为2m/s，表示物体做匀速直线运动．故A错误．

B、从t=0s到t=2s 物体加速度的大小为a=

△v
△t
=
2
2
m/s2=1m/s2．故B正确．

C、从t=4s到t=6s物体做正方向的匀减速直线运动．故C错误．

D、从t=0s 到t=6s 物体的位移等于图象梯形的“面积”，显然不等于零．故D错误．

故选B

多项选择题

患者女性，22岁。行超声卵泡监测，成熟卵泡的声像图特点有（）.

A.生理情况下常为双侧卵巢内同时出现

B.内部透声差

C.移向卵巢表面并向外突出

D.外形饱满，壁薄

E.直径>16mm
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单项选择题

It was a very hot day in the middle of summer, and there were no trees along the street. Mr. Read (41) his shop at half past five, and went out into the street and began walking to the bus. He was a very (42) man. The sun shone straight down the street, and in a few minutes Mr. Read (43) very hot.

A. opened B. reached C. closed

A small boy came out of another (44) in the street and followed Mr. Read. He stayed very (45) him all the time, and he kicked Mr. Read’s (46) several times. Mr. Read looked at him angrily each time.After the fourth time, Mr. Read stopped, turned (47) and said to the small boy, "What are you doing (48) following me like that! You’re going to hurt my feet."
"I’m (49) , but don’t stop me, please!" the small boy said. "It’s very hot today, and there isn’t (50) shade anywhere else in the street!\
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