什么是断路？

阅读理解。

     In the 13th century, the famous Italian traveler, Marco Polo, traveled a long way to China. During his

stay in China, he discovered that the Chinese used paper money. In western countries, people did not use

paper money until the 15th century.

     A Chinese man called Cai Lun invented paper almost 2000 years ago. He made it from wood.

     Now paper still comes from trees. We use a lot of paper every day. Every day, people throw away

about 280 tons of paper in our city. It takes 17 trees to make one ton of paper. This means that we are

cutting nearly 4800 trees every day. Since it takes more than 10 years for a tree to grow, we must start

using less paper now. If we don't, we will not have enough time to grow more trees to take the place of

those we use for paper. 

     So how can we save paper? We can use both sides of every piece of paper, especially when we are

making notes. We can choose drinks in bottles instead of those in paper packets. We also use cotton

handkerchiefs and not paper ones. When we go shopping, we can use fewer paper bags. If the shop

assistant does give us a paper bag, we can save it and reuse it later.

1. Who was Marco Polo? [ ]

A. He was a traveler of Italy.

B. He was an inventor of Italy

C. He discovered how to use paper money

D. He stayed in China

2. People in western countries first used paper money in the ______ century. [ ]

A. 15th

B. 13th

C. 7th

D. 17th

3. How many trees does it take to make one ton of paper? [ ]

A. 10

B. 17

C. 280

D. 4800

4. Which of the following is not the way of saving paper? [ ]

A. To use both sides of every piece of paper.

B. To grow more trees.

C. To use cotton handkerchiefs instead of paper ones.

D. To use the paper bags from shops more than once.

5. Which is the best title of the passage? [ ]

A. Saving Paper

B. Cai Lun, the Great Inventor

C. Handkerchiefs Back Again

D. Story of Paper

2009年9月21日至25日，胡 * * * * 出席第64届联合国大会一般性辩论、安理会核不扩散与核裁军问题峰会和20国集团领导人匹兹堡峰会。我国领导人高度重视并积极参与这些国际会议表明今天的中国[     ]

①是一个和平、合作、负责任的大国

②是世界上最强大的国家

③在维护世界和平、促进经济发展方面发挥着重要作用

④在国际舞台上扮演着越来越重要的角色

A．①③④

B．②③④

C．①②③

D．①②④

国际储备资产的币种管理中，应考虑的主要因素不包括( )。

A．币值稳定性

B．货币盈利性

C．使用方便性

D．国际政治安全因素

下列选项中，对证券投资基金的投资进行限制的主要目的是( )。

A．引导基金分散投资、降低风险

B．避免基金操纵市场

C．发挥基金引导市场的积极作用

D．增加基金资产的收益水平

我国节能工作存在的主要问题是什么？