MMPI-2包括10个临床量表和7个效度量表，它们均属于( )的内容。A．附加量表

一个弹簧振子沿x轴做简谐运动，取平衡位置O为x轴坐标原点。从某时刻开始计时，经过二分之一周期，振子具有沿x轴正方向的最大加速度。能正确反映振子位移x与时间t关系的图像是

Those postcards were so lovely that they_________ in no time.

A．sold

B．had been sold

C．were sold

D．have been sold

阅读理解。

    Sure, a teenager who works part-time may be learning something about responsibility, teamwork and

money management. But research has shown that when teens work for 20 hours or more a week, as nearly

half of US 12th graders do during the school year, the job isn't just good practice for the future. Overworked

teens give up some sleep and exercise, spend less time with their families, and cut back on their homework.

    That is not even the worst of it. A 2008 report by the National Research Council and the Institute of

Medicine showed that students who worked 20 hours a week had lower grades, higher dropout rates (退学率),

and were less likely to go to college.

     Most of these hardworking teens get jobs in the service industry, with more than half employed in

restaurants and stores. A quarter of them are employed in the health-care industry, while 8% work in

agriculture.

     Soon, teens may not be the ones deciding how many hours a week they want to spend on part-time jobs.

A labor agency has asked Congress (国会) to give the US Department of Labor instructions to limit the

number of hours youngsters under age 18 work during the school year, and Congress has agreed to.

     If you'd like tips on employment guidelines and teen employment, send away for the Parents Primer: When

Your Teen Works. Mail $1 and your written request to the National Consumers League, 1701 K Street, NW,

Suite 1200, Washington, DC 20006.

1. Study shows spending a lot of time on part-time jobs _____. [ ]

A. doesn't improve a teen's sense of responsibility

B. is harmful to teens in several aspects

C. helps a teen to concentrate on his study

D. only helps teens to make more money

2. The author wrote Paragraph 2 to _____.[ ]

A. support the result of the study with some facts

B. tell us the proper time for doing part-time jobs

C. give a good example of doing a part-time job

D. show why students don't like studying

3. What kind of part-time job do most teens take according to the passage? [ ]

A. Working on a farm

B. Working in the service industrysnoper@163.com

C. Working as nurses in hospitals

D. Working in factories

4. From the passage we learn that _____.[ ]

A. teens won't be allowed to work part-time soon

B. teens can decide how many hours week they want to spend on part-time jobs

C. the US Department of Labor isn't responsible for teens working part-time

D. the amount of time that students under 18 spend on part-time jobs will be limited

钢结构安装前，基础混凝土强度应达到设计强度的（）以上。

A.55%

B.50%

C.75%

D.85%