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问题 单项选择题

缺血性卒中的TOAST分型中，相对少见的类型是（）.

A.心源性脑栓塞

B.大动脉粥样硬化性卒中

C.小动脉卒中（腔隙性脑梗塞）

D.其他原因引发的缺血性卒中

E.不明原因的卒中

答案

参考答案：D

选择题
如图所示，在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场，一个不计重力的带电粒子从坐标原点O处以速度v进入磁场，粒子进人磁场时的速度方向垂直于磁场且与x轴正方向成120°角，若粒子穿过y轴正半轴后在磁场中到x轴的最大距离为a，则该粒子的比荷和所带电荷的正负是（　　）

A．，正电荷

B．，正电荷

C．，负电荷

D．，负电荷
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填空题

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. Wahlquist 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 continue to______(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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