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问题 多选题

如图甲所示，在一条电场线上有A、B两点，若从A点由静止释放一电子，假设电子仅受电场力作用，电子从A点运动到B点的速度-时间图象如图乙所示，则（　　）

A．电子在A、B两点受的电场力FA＜FB

B．A、B两点的电场强度EA＞EB

C．A、B两点的电势φA＜φB

D．电子在A、B两点具有的电势能EPA＜EPB

答案

根据题意，电子从静止释放后从A运动到B，则电子受到的电场力方向从A→B，而电子带负电，电场线方向从B→A，则B点的电势大于A点的电势，即φA＜φB．故C正确

从速度图象看出，电子从A运动到B过程速度增大，加速度变化，电场力减小，即FA＞FB，场强变小，则B点的场强小于A点的场强，即EA＞EB．故A错误，B正确；因电场力做正功，则电势能减小，故D错误．

故选：B　C

单项选择题

检验粪便中的寄生虫体应()。

A．取不同部位的粪便

B．留取全部粪便

C．留取少许粪便

D．取脓血及黏液部分粪便

E．粪便置于加温容器中立即送检
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填空题


In the following passage, there are 25 blanks representing words that are missing from the context. You are to put back in each of the blanks the missing word. Write your answers on the ANSWER SHEET. The time for this section is 25 minutes.
Of all the employed workers in the United States, 12.5 million are part of a temporary workforce. The United States Bureau of Labor Statistics counts 9.2 percent of workers as those who have (1) they term "alternative employment arrangements." The government predicts that temporary staffing agencies (2) experience growth of 49 percent by 2010. If numbers increase at the rate (3) , these companies will add 1.9 million new jobs by 2010. That’s more than any (4) industry.
Temporary workers were the first ones to be affected by the recent economic recession, but they are (5) to be the first to regain positions as the economy picks up and companies work to rebuild. Employers use temporary workers as a resource because (6) offer
flexibility and come at a low cost. Many temporaries are categorized as "independent contractors" instead of employees, (7) allows the employer to avoid (8) certain taxes. Because they are not required to offer benefits to temporary workers, companies can save a great deal of money by hiring temps. Usually, temporary workers can qualify (9) benefits if they work for a staffing company for a certain length of time. Most temps, however, do not continue with one company long (10) to qualify for them because they regard the position as a step on the ladder to a (11) position later.
According to Richard Wahlquist, president of the American Staffing Association, 75 (12) of temporary workers hope for transition out of the temporary staffing category (13) a period of time. Wahlquist finds that temporary workers spend about 11 weeks on various assignments before their (14) out of the temporary workforce. Many use temporary positions to gain experience and skills (15) they move on to better jobs. Wahquist says that the temp workforce as a whole turns (16) 400 percent each year.
Tom Dilworth, research director at the Employment Policies Institute, explains (17) some workers like having temporary jobs (18) it affords them a great deal of elasticity with time and everything. Some temps only have a limited (19) of time to work and temp agencies can help coordinate jobs to fit their schedules. Other sometimes-employees use temporary jobs to get an (20) to a company from the inside, to get a foot in the door of a certain business or career. (21) others take temporary positions in hopes their employers will change them over to permanent positions eventually.
Nearly all the industries in the United States use temporary workers. (22) to Tim Costello, coordinator of the North American Alliance for Fair Employment, the growth of temporary labor threatens (23) job security of permanent workers who fear replacement,as well as the temps who are more accustomed to turnover. He predicts that there will continueto (24) a gradual shift from permanent employees to contingent staffing, and that such a (25) in workplace demographics will "lead to lower wages, poorer working conditions, and more instability."

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