(15分)交管部门强行推出了“电子眼”,机动车违规现象大幅度减少.现有甲、乙两汽

题型:计算题

问题:

(15分)交管部门强行推出了“电子眼”,机动车违规现象大幅度减少.现有甲、乙两汽车正沿同一平直马路同向匀速行驶,甲车在前,乙车在后,行驶速度v0均为54km/h.当两车快要到十字路口时,甲车司机看到红灯亮起,于是紧急刹车,乙车司机看到甲车刹车后也紧急刹车(乙车司机的反应时间=0.4s,反应时间内视为匀速运动).已知甲车、乙车紧急刹车时产生的加速度大小分别为

(1)若甲司机看到红灯时车头距警戒线,要避免闯红灯,他的反应时间不能超过多少?

(2)乙车刹车后经多长时间速度与甲车相等?

(3)为保证两车在紧急刹车过程中不相撞,甲、乙两车刹车前的距离x0至少多大?

考点:匀变速直线运动
题型:计算题

阅读下列短文,从每题所给的四个选项(A、B、C和D)中,选出最佳选项

“Who needs a shopping mall if you have Taobao?” said Wang Lin, 28, a writer in Beijing.

Taobao, China’s largest online shopping site, has become an important part of Wang Lin’s life. She spends lots of money on Taobao.

A growing number of Chinese Internet users like Wang Lin have found the joys of online shopping. Most online shoppers are students or young people. More women shop online than men. Clothing and home-use products (产品)are the most popular online.

It was reported that more than 250 billion yuan was spent on online shopping last year, 80% through Taobao.

Taobao means “looking for treasure” in Chinese. People can find almost everything they need on Taobao, from clothes to books, from candies to DVD players.

You may question the security(安全)of online shopping, Wang Lin said, “It’s very safe and convenient. Unless(除非) you receive the products from the sellers and are satisfied with them, the shop owner will not get the money. You can also get your money back if you want to return the products.”

小题1:What products are the most popular online?

A.Candies and DVD players.

B.Treasure products.

C.Clothing and home-use products.

D.Clothes and books.小题2:Taobao is______.

A.a shopping mall

B.an online shopping site

C.an online shopper

D.the China’s largest website小题3:In the last paragraph, the underlined word “them” refers to “______”.

A.shop owners

B.products

C.sellers

D.online shops小题4:Which is the best title of the passage?

A.Wang Lin’s life

B.Shopping online is not safe

C.China’s online shoppers

D.Online shopping in China

题型:计算题

硫硫酸有______性,通常用它作干燥剂;碳酸钠溶于水,其水溶液显______性,工业上称它为纯碱.

题型:计算题

    图示区域自然资源丰富周家间的合作发展潜力巨大。位于图中的我国传统工业基地建国初期在国民经济建设中具有重要地位。

(1)图中A城市崛起于20世纪60年代,崛起和发展的原因是 ______________。

(2)B湖是___________湖。

(3)拟建中自B湖附近东去的能源运输线,其经济合理的运输方式应为______________。

(4)图中的等值线为400mm等降水量线,线两侧植被类型不同,据此填写下表。

题型:计算题

生产者价格指数,是工业生产产品出厂价格和购进价格在某个时期内变动的相对数,反映全部工业品出厂和购进价格的变化趋势及幅度。目前,中国以工业品出厂价格替代生产者价格。

题型:计算题

决策系统的发展从技术层次上可划分为:专用的决策系统、决策支持系统生成器和 ______。

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