问题 选择题

关于宇宙速度,下列说法哪些是正确的

A.第一宇宙速度等于7.9km/s

B.第一宇宙速度是人造卫星环绕地球表面做匀速圆周运动的最小速度

C.第二宇宙速度是卫星挣脱地球的束缚所需的最小速度

D.第三宇宙速度是卫星挣脱地球的束缚所需的最小速度

答案

AC

第一宇宙速度数值是7.9km/s,是环绕地球的最大速度,发射卫星的最小速度,A对;第二宇宙速度是脱离地球引力的最小发射速度,C对;第三宇宙速度是脱离太阳系的最小发生速度,D错;

阅读理解

阅读理解。

     One day the employees of a large company in St Louis, Missouri returned from their lunch

break and were greeted with a sign on the front door. The sign said: "Yesterday the person

who has been hindering (阻碍) your growth in this company passed away. We invite you to

join the funeral (葬礼) in the room that has been prepared in the gym."

     At first everyone was sad to hear that one of their colleagues had died, but after a while

they started getting curious about who this person might be.

     The excitement grew as the employees arrived at the gym to pay their last respects. Everyone

wondered: "Who is this person that was hindering my progress? Well, at least he's no longer here."

     One by one the employees got closer to the coffin (棺材) and when they looked inside it they

became speechless. They stood over the coffin, shocked and in silence, as if someone had touched

the deepest part of their soul.

    There was a mirror inside the coffin. Everyone who looked inside it could see himself. There

was also a sign next to the mirror that said: "There is only one person who can set limits to your

growth: it is YOU."

     You are the only person who can revolutionize (彻底改变) your life. You are the only person

who can influence your happiness, your realization and your success. You are the only person who

can help yourself.

    Your life does not change when your family changes, when your friends change, when your boss

changes, and when your company changes.

    Your life changes when you change, when you go beyond your limiting beliefs, when you realize

that you are the only one responsible for your life.

1. The writer's purpose in writing the article is to tell us that ________.

A. the harder we work, the more successful we will become

B. our work and life are closely connected with others

C. changing our lives is down to ourselves

D. we will have a better future if people do not hinder our development

2. People were speechless when they looked inside the coffin because ________.

A. there was nothing but a mirror inside

B. they could see their own souls inside

C. their closest colleague lay inside

D. what was inside told a great truth

3. Who probably wrote the sign on the front door?

A. The company boss.

B. A worker who liked to make fun of others.

C. The director in charge of production.

D. A worker who wanted to teach others a lesson

4. What can we conclude from the article?

A. The employees went to the gym to join the funeral.

B. The lesson the employees learned would influence them greatly.

C. The employees' lives depended on the attitude of their boss.

D. The employees got angry after the funeral.

问答题 简答题