计算机病毒所造成的危害是A．破坏计算机系统软件或文件内容 B．造成硬盘或软盘物理破损

阅读理解。

    One morning an old man left his house with six donkeys (驴). After a while (过了一会儿), he got tired

and got on one of them.He counted (数) the donkeys and there were only five. So he got off (下来) and

went to look for the sixth. He looked and looked, but he did not find it, so he went back to the donkeys

and counted them again. To his surprise (令他惊讶的是), this time there were six. So he got on one of

them again and they started. After a few minutes, he counted the donkeys again and again there were only

five!He became confused (困惑的). Just then a friend of his passed him. The old man said to him, "I left

my house with six donkeys. Then I had five, then I had six again, and now I have only five! One, two,

three, four, five." 

    "But," said his friend, "you are sitting on a donkey, too. This is the sixth. And you are the seventh!"

1.When did the story happen (发生)? [ ]

A.In the morning

B.In the afternoon

C.In the evening

D.At night

2.In fact, how many donkeys were there? [ ]

A.Four

B.Five

C.Six

D.Seven

3.Why did the old man get on one of the donkeys? [ ]

A.Because he wanted to count them

B.Because he got tired

C.Because he wanted to look for the sixth

D.Because he became confused

4.Why couldn't the old man get the right number? [ ]

A.Because he left one at his house

B.Because he gave one of the donkeys to his friend

C.Because he didn't see one of the donkeys

D.Because he forgot to count the one he got on

5.The old man was very            .[ ]

A.kind

B.foolish (愚蠢的)

C.smart

D.surprised

关于正常椎间盘信号，以下说法正确的是（）

A．在T2WI上髓核和内纤维环呈高信号，外纤维环呈高信号 

B．在T2WI上髓核和内纤维环呈低信号，外纤维环呈高信号 

C．在T2WI上髓核和外纤维环呈高信号，内纤维环呈低信号 

D．在T2WI上髓核和内纤维环呈高信号，外纤维环呈低信号 

E．在T1WI一髓核和内纤维环呈高信号，外纤维环呈低信号 

病人男性，19岁，在校大学生。在寝室聊天时突然倒地，意识丧失，抽搐，口吐白沫，尿失禁。20分钟后逐渐恢复，对所发生的事情全然不知。

病人最可能的诊断是（）

A.营养失调

B.低血糖

C.癫痫

D.低血压

E.劳累过度

[选做题]]如图所示，两根正对的平行金属直轨道MN、M′N′位于同一水平面上，两轨道之间的距离 l=0.50m．轨道的MM′端之间接一阻值R=0.40Ω的定值电阻，NN′端与两条位于竖直面内的半圆形光滑金属轨道NP、N′P′平滑连接，两半圆轨道的半径均为 R₀=0.50m．直轨道的右端处于竖直向下、磁感应强度B=0.64T的匀强磁场中，磁场区域的宽度d=0.80m，且其右边界与NN′重合．现有一质量 m=0.20kg、电阻 r=0.10Ω的导体杆ab静止在距磁场的左边界s=2.0m处．在与杆垂直的水平恒力 F=2.0N的作用下ab杆开始运动，当运动至磁场的左边界时撤去F，结果导体ab恰好能以最小速度通过半圆形轨道的最高点PP′．已知导体杆ab在运动过程中与轨道接触良好，且始终与轨道垂直，导体杆ab与直轨道之间的动摩擦因数 μ=0.10，轨道的电阻可忽略不计，取 g=10m/s²，求：

（1）导体杆刚进入磁场时，通过导体杆上的电流大小和方向；

（2）导体杆穿过磁场的过程中通过电阻R上的电荷量；

（3）导体杆穿过磁场的过程中整个电路产生的焦耳热．