如图所示,一木块放在水平桌面上,在水平方向受到二个推力的作用,木块处于静止状态。

题型:选择题

问题:

如图所示,一木块放在水平桌面上,在水平方向受到二个推力的作用,木块处于静止状态。其中F1=10 N,F2=2 N。若撤去力F1,则木块受到的摩擦力的大小和方向。(     )

A.8N,水平向左

B.8N,水平向右

C.2N,水平向右

D.2N,水平向左

考点:静摩擦力滑动摩擦力、动摩擦因数
题型:选择题

五代十国时期在北方和东北地区建立辽王朝的少数民族()

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下列因果关系成立的是(  )

A.由于HF分子间存在氢键,所以HF的沸点比HCl、HBr都高

B.由于14C和12C具有相同质子数不同中子数,所以二者互为同素异形体

C.由于硝酸具有强氧化性,所以不能用稀硝酸和大理石反应制二氧化碳

D.由于铁和硫酸能发生反应,所以不能用铁罐车储运浓硫酸

题型:选择题

Two Christmas traditions have come under attack in recent years from environmentalists: Christmas cards and Christmas trees.

Paper cards are seen as wasteful and, for some people, going card-free is another way of going green. They also argue that in a world of e-mail, Skype, Facebook and Twitter, people are in touch all the time anyway; they no longer need the yearly card that connects them with long lost friends. If you want to send Christmas greetings, there are free e-cards, which get the job done with no postage or wasted paper.

However, especially for people who didn’t grow up with e-mail, there is something missing from a Christmas e-mail. The first Christmas cards appeared in London in 1843 and were designed by the same man who had introduced the world’s first postage stamp three years earlier. His name was Sir Henry Cole.

They rose in popularity throughout the 20th century. Many people sent cards that were sold for charity. The most famous of these are the ones sold for UNICEF. In the UK this year, in the three weeks before Christmas, the post office expects to handle 100 million cards every day. Environmental awareness also means that nowadays many people recycle their cards; this helps raise money to plant more trees, as well as recreating more paper.

When we think of trees at Christmas, there is one that immediately springs(跃入)mind---the evergreen tree that people decorate with ornaments and place their presents under. The custom dates back almost a thousand years to Germany. Nowadays 33 to 36 million Christmas trees are produced in America and 50 to 60 million in Europe each year. Some trees are sold live with roots and soil so people can plant them later and reuse them next year.

Some people prefer artificial trees as they are reusable and much cheaper than their natural alternative. However, environmentalists point out that they are made from petroleum (石油) products and so have many pollution issues.

小题1:What is the main idea of the article?

A.To introduce the history of two typical Christmas traditions.

B.To explain the debate about some Christmas traditions.

C.To analyze how two Christmas traditions grew in popularity.

D.To point out the problems caused by celebrating Christmas.小题2:What does the underlined word “They” in the fourth paragraph probably mean?

A.Many people

B.Christmas e-mails

C.Postage stamps

D.Christmas cards小题3:Some people suggest getting rid of paper cards because     .

a. they cannot be recycled         b. they are not environmentally friendly

c. they are mostly sold for charity  d. the e-cards have many advantages over them

e. they are not as necessary as they used to be for people

A.a, b, d

B.a, c, d

C.b, d, e

D.b, c, e小题4:What can we conclude from the article?

A.The first Christmas cards were designed earlier than the world’s first stamps.

B.This year has seen a dramatic drop in Christmas card sales.

C.Environmentalists advise people to buy cards that are sold for charity.

D.Growing environmental awareness is encouraging people to recycle their cards.小题5:Which of the following statements in TRUE according to the article?

A.There is always a wider Christmas tree market in America than in Europe.

B.The custom of decorating Christmas trees first appeared in Britain.

C.Some people prefer to buy live trees that can be reused next year.

D.Artificial trees are better than natural ones in all aspects.

题型:选择题

被柏拉图称为“第十位文艺女神”的诗人是()。

A.维吉尔

B.贺拉斯

C.萨福

D.奥维德

题型:选择题

属于卫生部公布的既是食品又是药品的名单中有()

A.蒲公英、淡竹叶、益智、刺五加

B.红花、枣、火麻仁、刺梨、灵芝

C.魔芋、蚕蛹、罗汉果、锁阳

D.昆布、榧子、决明子、莱菔子

E.人参、刺五加、枸杞

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