20世纪初，爱因斯坦相对论的提出是物理学的一场变革。它

   “Who needs a shopping mall if you have Taobao?” says Wang Lin, 28, a writer in Beijing.
     Taobao, China's largest online shopping web 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 have found the fun of online shopping. Most online shoppers are students or young workers. More women shop on line than men. Clothing and home-use products are the most popular on line.
     It was reported that more than 250 billion(十亿) yuan was spent on online shopping last year, 80% through Taobao.
    Taobao means “looking for treasure(珠宝)” in Chinese. People can find almost everything they need on Taobao, from clothes to books, from candies to DVD players.
     You may ask the security of online shopping, Wang Lin said, “It's very safe and convenient. Unless you receive the products from the sellers and are satisfied(满意的) with them, the shop owner will not get the money. You can also get your money back if you want to return the products.”

A: Good morning, Bill.

B: Hi, Nick.

A: ____

B: Yes, I like playing basketball. How often do you exercise?

A: ____

B: Do you get up early in the morning?

A: Yes, I get up at 6:30 every morning. And then I play basketball for half an hour.

B: ____

A: I go to bed at 10:00. ____

B: I see. You look strong. Let's play basketball together tomorrow morning, OK?

A: All right. ____ See you.

B: See you tomorrow.

自行车是同学们常用的交通工具，请把对应题号填在横线上．

①通过增大压力来增大摩擦的是 ____ ；

②通过增大接触面的粗糙程度来增大摩擦的是 ____ ；

③通过加润滑油来减小摩擦的是 ____ ；

④通过用滚动代替滑动来减小摩擦的是 ____ ；

A．脚蹬子表面做的粗糙不平；

B．刹车时要用力捏闸

C．车轮做成圆形的；

D．要经常给链条上油．