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问题 填空题

一台激光器发光功率为P0，发出的激光在真空中波长为，真空中的光速为，普朗克常量为，则每一个光子的能量为      ；该激光器在时间内辐射的光子数为       。

答案

  hC/λ     ；  P0tλ/ hc

每一个光子的能量为，该激光器在时间内辐射的光子数为

故答案为：，

单项选择题 B型题

抗酸染色阳性的细菌是（）

A.金黄葡萄球菌

B.难辨梭状芽孢杆菌

C.铜绿假单胞菌

D.牛型结核分枝杆菌

E.克雷伯杆菌
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单项选择题

Visitors to this country are normally admitted for six months, but foreign students can usually stay for one year. They must (51) an educational institution, and they are required to study for a minimum of fifteen hours a week on a (52) course. Prospective students have to show that they can afford their studies, and that they have sufficient (53) resources to support themselves (54) in this country.

In order to work here the foreigner needs a work permit, (55) must be applied for by his prospective employer. The problem here is that the Department of Employment has the right to grant or (56) these permits, and there is little that can be done (57) it; it would be extremely unwise for a foreign visitor to work (58) a permit, since anyone doing so is liable to immediate deportation (驱逐出境). There are some people from the Common Market countries, who are often given (59) residence permits of up to five years. Some other people, such as doctors, foreign journalists, authors and others can work without permits, and foreign students are normally allowed to (60) part-time jobs while they are studying here.

54().

A.after 

B.but 

C.while 

D.before
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