问题 问答题 简答题

阐述电梯平层大的原因。

答案

参考答案:

1.选层器换速触头与固定触头位置不合适;

2.平层感应器与隔磁板的相对位置发生变化;

3.制动器弹簧过松:制动带磨损:松闸间隙大:制动带或制动轮有污垢;

4.个别继电器,接触器有延时释放现象;

5.电梯超载;

6.换速过晚;

7.曳引绳过度润滑,曳引轮绳槽磨损,曳引绳打滑。

阅读理解

阅读理解

      American teens are setting an example for their parents through their volunteer work, according to

the Harris Interactive poll conducted in the United States between Jan.29 and Feb.2 among 2,003 adults.

The random national telephone survey released this week by the Federal Waybased charity World Vision

found that more teens volunteer to support a charitable (慈善的) cause-56 percent-than have a parttime

job-39 percent.

      Parents and guardians said 82 percent of the teens in their lives do something to support charitable

causes, including volunteering, recruiting others to a cause, wearing a Tshirt or donating money.Fortysix

percent of the adults surveyed said they volunteered their time and they also inspired their children to

volunteer.

Sara Johnson, a teacher who advises students at a private school in a Chicago suburb, says she's seen a

rise of teen involvement in social causes since President Barack Obama was elected in November.

      The Harris Interactive survey found a quarter of teens have become more involved in charitable

causes or organizations as a result of the economic downturn, but the economy has also led to cuts in

allowances, and has teens work more hours at a paying job.

      Alynn Woodson, director of volunteer engagement at Habitat for Humanity International, said she

has noticed a new enthusiasm among teen volunteers for the organization.

      Habitat for Humanity International celebrates the 20th anniversary of its alternative spring break

program this year and is expecting more than 12,000 young people to help build homes for lowincome

people around the nation.

1. The following statements about the teens' voluntary work are true EXCEPT________.

A. the economic downturn led teens to work less hours at paying jobs

B. the poll was done at the end of January and the early February

C. children do more voluntary work than their parents

D. more teens are involved in charitable causes or organizations

2. We can infer from the passage that________.

A. parents and guardians encourage their children to do voluntary work

B. volunteers all wear Tshirts while doing charity work

C. more teens are doing paying jobs as a result of the economic downturn

D. less teens were enthusiastic about voluntary work before Obama came into power

3. The author mentioned Habitat for Humanity International in order to prove________.

A. that homes for lowincome people will be built around the nation

B. Alynn Woodson is the director of volunteer engagement

C. more young people are doing volunteer work

D. it's 20 years since Habitat for Humanity International came into being

4. Which of the following is the best title of the passage?

A. More teens doing voluntary work

B. Teens setting examples for parents in charitable causes

C. Comments on teens' voluntary work

D. The 20th anniversary of Habitat for Humanity International

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