问题 解答题

甲、乙两人同时从同一地点出发骑车前往相距40千米的某地,甲比乙每小时多行驶2千米,甲骑到距目的地4千米的地方因故改为步行,每小时比原来慢了8千米,结果两人同时到达,求甲、乙两人的骑车速度各是多少?

答案

解:设乙骑车速度为xkm/h,则甲骑车速度为(x+2)km/h,甲步行速度为(x+2-8)km/h,根据题意,得

解得x=10,

经检验,x=10是原方程的解,且符合实际意义,

所以,当x=10时,x+2=10+2=12(km/h)

答:甲骑车速度为12km/h,乙骑车速度为10km/h。

选择题
阅读理解

Never give out identifying information such as Name, Home Address, School name, or Telephone Number in a public message such as at a chat room or on bulletin bards. Never send a person a picture of you without first checking with your parents or guardian.

● Never respond to messages or bulletin board items that are: Suggestive / Obscene / Belligerent / Threatening / Make You Feel Uncomfortable.

● Be careful when someone offers you something for nothing, such as gifts and money. Be very careful about any offers that involve your coming to a meeting or having someone visit your house.

● Tell your parents or guardian right away if you come across any information that makes you feel uncomfortable.

● Never arrange a face-to-face meeting without telling your parents or guardian. If your parents or guardian agree to the meeting, make sure that you meet in a public place and have a parent or guardian with you.

● Remember that people online may not be who they seem. Because you can’t see or even hear the person, it would be easy for someone to misrepresent him or herself. Thus, someone indicating that“she”is a“12-year-old-girl”could in reality be an older man.

● Be sure that you are dealing with someone that you and your parents know and trust before giving out any personal information about yourself via E-mail.

● Get to know your“online friends”just as you get to know all of your other friends.

小题1:We can infer from the passage that            .

A.it is not safe to surf the internet

B.people now are no longer honest

C.we can chat with unfamiliar people online

D.people online are not who they are小题2:Which of the following is right according to the passage?

A.People online never tell their friends their real names.

B.You can often get something free from the internet.

C.Your friends online may want to meet you.

D.Online friends are not friends at all.小题3:What is the main idea of the passage?

A.How to surf the internet.

B.Kids shouldn’t surf the internet.

C.How to choose online friends.

D.How to protect yourselves online.