问题 选择题

重为400N的木箱放在水平地面上,木箱与地面的最大静摩擦力是85N,动摩擦因数是0.2,如果分别用50N、90N的水平力推木箱,则木箱受到的摩擦力分别是(  )

A.50N,90N

B.50N,80N

C.0N,80N

D.50N,85N

答案

F=50N<85N,知50N的水平力推不动木箱,木箱受到的是静摩擦力,根据水平方向上的二力平衡,知静摩擦力大小为50N.

    F=90N>85N,知木箱被推动,受到的是滑动摩擦力,f=μFN=μmg=80N.故B正确,A、C、D错误.

故选B.

阅读理解

阅读理解。

     Many English learners have difficulty deciding what kind of English accent they want to have. A US

accent, perhaps modeled on the way a Hollywood star speaks? Or maybe you want to imitate (模仿) the

British accent of a BBC news reader?

     Young British people find the US accent attractive while young US people like a British accent. Especially

when the person speaking is of the opposite sex! Let's listen to what they have to say. Stephen Yang, 17, from

London, UK A US accent is cute, especially when a girl speaks it. Whether it's Jessia Alba speaking or the

girl- next-door, the way US girls speak has a sweet tingle that is really sassy (时髦). A girl from Texas recently moved into our neighborhood. Her Texan twang (鼻音) had all the boys here on their knees within seconds of

meeting her.

      To me, accents reflect the attitudes, characteristics and lifestyles of the people. Jennifer Sun, 16, from

New Jersey, US From watching English actors like Daniel Radcliffe, my friends and I have developed a soft

spot for British men. Some are attracted to the qualities of English males, while others admire their sense of

style.

     Everyone, however, agrees that the most appealing aspect of an English man is his accent. For example,

many American girls watch Harry Potter movies over and over again just to listen to the actors speak. The

English accent seems almost like art.

1. In Stephen Yang's opinion, accents just show_______.

A. the beauty of the language

B. how the language is spoken

C. the cultural differences of the speakers

D. the fashion of the day

2. The underlined word "cute" probably means_______.

A. strange

B. exciting

C. attractive

D. fashionable

3. Many American girls watch Harry Porter again and again in order to ________.

A. learn the acting skills of the these stars

B. learn the magic performed by Harry Potter

C. imitate the actors' accents

D. know more about British English

4. What is probably the best title for this passage?

A. British English and American English

B. British Accent or American Accent

C. American English Accent is Most Accepted

D. The difference between British Accent and American Accent.

单项选择题