问题 选择题
如图所示,在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场,一个不计重力的带电粒子从坐标原点O处以速度v进入磁场,粒子进人磁场时的速度方向垂直于磁场且与x轴正方向成120°角,若粒子穿过y轴正半轴后在磁场中到x轴的最大距离为a,则该粒子的比荷和所带电荷的正负是(  )

A.,正电荷

B.,正电荷

C.,负电荷

D.,负电荷

答案

答案:C

单项选择题
完形填空

第二卷(非选择题 共35分)

注意事项:

用0.5毫米黑色签字笔在答题卡上作答。在试卷上作答,答案无效。 

第四部分 写作(共两节,满分35分).

第一节 短文填词(共10小题;每小题1分,满分10分)

阅读下面短文,根据以下提示:1)汉语提示,2)首字母提示,3)语境提示,在每个空格内填入一个适当的英语单词,并将该词完整地写在右边相对应的横线上。所填单词要求意义准确,拼写正确。

What would you do if you failed? Many people may choose to give  ______ .    76.____

However, the surest way to success is to keep your direction      and s_____         77.____

to your goal.On your way to success, you must keep your direction.It is just like a lamp,

g        you in darkness and                78.____

helping you ______(克服)difficulties on your way.Otherwise, you           79.___

will easily get lost or hesitate to go       (向前).Direction means          80.______

objective, you can get nowhere        an aim in life.You can                81.__   

try to write your aim on paper and make some p       to achieve              82.______

it.In this way, you will know _______ to arrange your time and to             83._____

spend time properly.And you should have a   (信念)that you             84.______

are sure to succeed as l       as you keep your direction.                        85.___