问题 多选题

如图所示,一内外侧均光滑的半圆柱槽置于光滑的水平面上,槽的左侧有一竖直墙壁。现让一小球(可是为质点)自左端槽口A点的正上方从静止开始下落,与半圆槽相切并从A点入槽内。则下列说法正确的是

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A.小球在槽内运动的全过程中,只有重力对小球做功

B.小球在槽内运动的全过程中,小球与槽组成的系统机械能守恒

C.小球从最低点向右侧最高点运动的过程中,小球与槽组成的系统水平方向上的动量守恒

D.小球离开右侧槽口以后,将做竖直上抛运动

答案

BC

阅读理解

Learning a Second Language

Some people learn a second language easily. Others have trouble learning a new language. How can you help yourself learn a new language, such as English? There are several ways to make learning English a little easier and more interesting.

The first step is to feel positive about learning English. If you believe that you can learn, you will learn. Be patient. You do not have to understand everything all at once. It is natural to make mistakes when you learn something new. We can learn from our mistakes. In other words, do not worry about taking risks.

The second step is to practice your English. For example, write a diary every day. You will get used to writing it in English, and you will feel comfortable expressing your ideas in English. Several weeks later, you will see that your writing is improving. In addition, you must speak English every day. You can practice with your classmates outside class. You will all make mistakes, but gradually you will become comfortable communicating in English.

The third step is to keep a record of your language learning. You can write this in your journal. After each class, think about what you did. Did you answer a question correctly? Did you understand something the teacher explained? Perhaps the lesson was difficult, but you tried to understand it.

You must be positive about learning English and believe that you can do it. It is important to practice every day and make a record of your achievements. You will enjoy learning English, and you will feel more confident in yourself.

小题1:To feel positive about learning English means _______.

A.if you are patient, you will learn

B.you can understand everything all at once

C.if you make mistakes, you can learn from your mistakes

D.if you believe you can learn, you will learn小题2:When you learn English, you do not need to ______.

A.be patient

B.make mistakes

C.express your ideas in English

D.understand everything all at once小题3:What is not helpful for you to enjoy learning English?

A.To communicate in English.

B.To worry about taking risks.

C.To think about what has been done after each class.

D.To make a record of the achievements.小题4:What is the main idea of this passage?

A.It is very important to learn a second language.

B.Some people learn a second language easily while other people do not.

C.There are ways to help you learn a second language more easily.

D.Don’t worry about taking risks when learning a second language.小题5:What does the underlined word “journal” in the 4th paragraphmean?

A.Diary

B.Composition

C.Poem

D.Newspaper

单项选择题