问题 问答题

汽车启动后做匀加速直线运动,它在第5s内行驶了18m,则它在第7s未的速度是(  )

A.18m/s

B.28m/s

C.26m/s

D.无法计算

答案

由于汽车做初速度为0的匀加速直线运动,设加速度为a,

则汽车在4s末的速度v1=at1=4a,

汽车在5s末的速度v2=at2=5a,

故汽车在第5s的平均速度

.
v
=
4a+5a
2
=
9a
2

故汽车在第5s的位移x=

.
v
t,即
9a
2
×1=18m,解得a=4m/s2

故汽车在第7s末的速度v=at=4×7=28m/s.

故B正确,

故选B.

阅读理解

English A

Because it’s never too late to start learning English Course structure and goals

A basic course that improves different English skills. Lessons focus on pronunciation of words and sounds, listening, practicing casual English, reading and combining all of these skills together.

We learn through introducing ourselves to friends and family, discussing everyday activities, food, restaurants, shopping and places.

This course is for People who have learned very little English in the past.

Duration(学时)

Class meets once a week over an 8-month period.

Moreover, students can take advantage of our extra lessons, for an additional hour per week.

At the end of the course the student will

● Understand sentences and phrases dealing with topics such as: personal and family information, shopping, geography, etc.

● Read short and simple sentences, find information in everyday texts, such as: advertising, menus, etc.

● Have short conversations.

● Communicate through simple everyday tasks.

● Describe their personal background, living conditions and other information about their surroundings.

● Write short and simple notes, messages and personal letters.

小题1:According to the passage, which of the following is TRUE?

A.You have to finish all the courses online.

B.You can get extra lessons for an hour a day.

C.The course includes different English skills.

D.Only children can join in this English course.小题2:The information of the passage is about         .

A.some ways to learn English well

B.a course for English beginners

C.the reasons for learning English

D.some advice from an English teacher小题3:After finishing this course, you can         .

A.know much about English countries

B.understand long and difficult English texts

C.talk about everything with foreigners freely

D.communicate with others in short conversations小题4:The passage is mostly likely to be found from a         .

A.novel

B.report

C.website

D.story

问答题 简答题