如下图所示,U形线框abcd处于匀强磁场中,磁场的磁感应强度为B,方向垂直于纸面

题型:选择题

问题:

如下图所示,U形线框abcd处于匀强磁场中,磁场的磁感应强度为B,方向垂直于纸面向内,长度为L的直导线MN中间串有一个电压表跨接在ab与cd上且与ab垂直,它们之间的接触是完全光滑的,R为电阻,C为电容器。现令MN以速度v0向右匀速运动,用U表示电压表的读数,Q表示电容器所带电荷量,C表示电容器的电容,F表示对MN的拉力,设电压表的体积很小,其中线圈切割磁感线对MN间的电压的影响可以忽略不计,则(    )

A.U=BLv0

B.F=0

C.U=0

D.F=v02B2L2/R

考点:电磁感应现象的综合应用
题型:选择题

患者女性,33岁,因“发现右腹股沟区肿块7天”来诊。患者髋关节活动时疼痛3个月,功能正常。否认外伤史,平常喜欢打网球。查体:右侧腹股沟可触及5cm×5cm肿块,较硬,界限清楚,固定;髋关节功能正常,关节穿刺少许褐色液体。实验室检查均正常。影像学检查:X线片示股骨头下部透亮区,边缘锐,边界清楚。强化CT示髋关节周围结节状软组织肿块,下内侧见股骨头溶骨性病灶约2cm×2cm。

软组织肿块和骨破坏的关系可能是()

A.骨转移

B.骨侵犯

C.多原发灶

D.卫星结节

E.跳跃性病灶

F.失用性

题型:选择题

第三部分:阅读理解(共20小题;每小题2分;满分40分)

阅读下列短文,从每题所给的四个选项(A、B、C、D)中选出最佳选项。

A

The first time I saw Carlos, I had my arms full of books and I was tearing into the classroom when I ran into something solid.It was Carlos.

"My, you're tall," he exclaimed. Of course, the class began to laugh.Annoyed, I walked to my seat without a word.

I glanced back to see if Reed Harrington was laughing with the rest.That would be the last straw.To my relief.Reed was studying and did not seem to be aware of it.I didn't know why I considered Reed my friend.Maybe just because he was a good two inches taller than I.

"Take that seat," Mr.McCarthy told the newcomer, pointing to the only empty one, in the back of the room.

Carlos smiled broadly."But I need a couple of dictionaries." Again the class laughed, but now they were laughing with Carlos, not at him.He had been here only 10 minutes and already he had them on his side.

It was the school election that made me think of Carlos again.Reed Harrington was voted president and Carlos vice-president."How come?" I kept asking myself."How come this shrimp (虾) who's only been in town for a little over a month gets to be so popular?"

So when I met Carlos this morning, I said to him, "It doesn't seem to bother you — being short, I mean." He looked up at me."Of course I mind being short.But there isn't anything I can do about it.When I realized I was going to have to spend my life in this undersized skin, I decided to make the best of it.My motto is — don't be afraid to be yourself."

56.This passage is mainly about a short boy who ____________.

A.won the school election       B.is ashamed of his height

C.has learned to accept his size   D.is embarrassed by the class

57.From the story, we can see that Carlos is ________.

A.shy but diligent    B.humorous and confident                                  

C.proud and popular        D.honest but sensitive

58.Paragraph 4 suggests that the author ______.

A.cared much about Reed's attitude

B.thought Reed was the same as the others

C.couldn't stand Carlos playing tricks on her 

D.hoped Reed was laughing with the others

59.According to the passage, what happened after the election?

A.Carlos and the author argued with each other.                                 

B.Carlos and Reed became very good friends.                            

C.The author changed her attitude toward Carlos.                                     

D.Carlos was elected president of the student committee.

题型:选择题

常量数学应用的局限性是什么?

题型:选择题

如图所示,倾角α=30°的等腰三角形斜面体固定在水平面上,一足够长的轻质绸带跨过斜面的顶端铺放在斜面的两侧,绸带与斜面间无摩擦.现将质量分别为M=4.0kg、m=2.0kg的小物块同时轻放在斜面两侧的绸带上.两物块与绸带间的动摩擦因数μ相等,且最大静摩擦力与滑动摩擦力大小相等,取重力加速度g=10m/s2

(1)若μ=

3
2
,试求两物块的加速度大小和方向;

(2)若μ=

3
6
,试求两物块的加速度大小和方向;

(3)若μ=

7
3
18
,试求两物块的加速度大小和方向.

题型:选择题

Windows的资源管理器窗口分为左右两个部分,其中 (1) 。在该窗口中,如果想一次选定多个不连续的文件或文件夹,正确的操作是先按住 (2) ,再用鼠标左键逐个选取。若已选定某文件,不能将该文件复制到同一文件夹下的操作是 (3) 。若已选定某文件,执行“删除”命令后,被删除的文件放在 (4) 中。

A.Alt键

B.Ctrl键

C.Shift键

D.Ctrl+Alt键

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