如图15-4-6所示,场强为E的匀强电场和磁感应强度为B的匀强磁场相互正交,一个

题型:问答题

问题:

如图15-4-6所示,场强为E的匀强电场和磁感应强度为B的匀强磁场相互正交,一个质子以速度v0以跟EB都垂直的方向从A点射入.质子质量为m,电荷量为e,当质子运动到c点时,偏离入射方向的距离为d.则质子在c点的速率为多大?

图15-4-6

考点:磁场对运动电荷的作用:洛伦兹力、左手定则
题型:问答题

中型空压机的排气量在10~100m3/min。()

题型:问答题

地球上有些动物将永远没有机会再让人类见到。这说明[ ]

A、动物繁殖能力不强            

B、自然界遭到破坏,人类应该保护自己的家园

C、人类应该和其他动物友好相处  

D、这些动物破坏了人类生活的环境,理应消失

题型:问答题

阅读理解。

     My grandfather is eighty years old. He always complains about how fast things have changed, and he

often says that life used to be better.

     "Families aren't what they used to be. A lot of families have broken up. If the husband and wife have

problems with their marriage, they no longer stay together. And mothers used to stay at home and take

care of their children, but now parents are both busy working. No one has time to look after children at

home.

     And the cars! No one walks anymore. More and more people drive. We used to walk five miles to

school on school days, even in winter. But now we don't. And in school, children don't have to think

anymore. In math class, for example, we used to add, subtract, multiply and divide by using our heads.

But now kids don't use their heads anymore. Instead, they use calculators.

     Most families have computers now. In the past we didn't have computers. We didn't even have lights.

My mother used to spend all day cooking in the kitchen. But now we don't often eat home-cooked food.

     And people talk less to each other than before. They are too busy to talk, too busy to eat, too busy to

think...Life used to be simple, but it isn't anymore."

1. What does the grandfather think of the life now? [ ]

A. It's as good as it used to be

B. It's worse than it used to be

C. It's better than it used to be

D. It's the same as it used to be

2. What does the underlined word "marriage" mean in Chinese?[ ]

A. 生活

B. 工作

C. 婚姻

D. 家庭

3. What did the grandfather used to do? [ ]

A. He used to use calculators in math class

B. He used to drive to school in winter

C. He used to go to school by bike

D. He used to walk five miles to school

4. What changes have happened?

    ① There are lights at home

    ② People often eat home-cooked food now

    ③ Lots of families have computers

    ④ More and more people drive instead of walking

A. ①②④

B. ②③④

C. ①②③

D. ①③④

5. Which of the following is TURE? [ ]

A. Life now is much simpler

B. People have more time to talk with each other now

C. The grandfather only complains and pays no attention to the better life now

D. Lots of mothers still stay at home and look after their children.

题型:问答题

“长夜难明赤县天,百年魔怪舞蹁跹,人民五亿不团圆。一唱雄鸡天下白,万方乐奏有于阗,诗人兴会更无前。”诗中的“一唱雄鸡天下白”是指

A.抗日战争的胜利

B.新中国的成立

C. * * 的结束

D.港澳的回归

题型:问答题

心肺脑复苏

更多题库