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问题 单项选择题

有计划的将抗菌药物分期分批次交替使用的目的是

A．使新出现的耐药基因不被药物选择而增多或让它们发生回复突变

B．处方如此设计能达到更好的治疗效果

C．考虑到生产厂商的利益分配

D．利于杀灭各种病原菌

E．有利于生产和节约抗菌药物

答案

参考答案：A

单项选择题

脑梗死的首要病因是（）

A.糖尿病

B.脑血管发育不良

C.脑动脉粥样硬化

D.脑血管炎

E.二尖瓣脱垂
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单项选择题

Personal computers are used by one person at a time. The largest personal computer, or PC.S, can fit on a (1) . Some of these (2) have more than one microprocessor. (3) the primary processor, which is a general-purpose device, a PC may have one or more processors to (4) special kinds of work. Some machines, (5) , have maths processors, others have graphics processors to help process photographs and other illustrations. Still others have (6) processors.

Office workers also use PCS that are not (7) to a network. These machines are used for (8) tasks as word processing, performing financial calculations, and organizing and (9) bodies of information called databases. People use PCS at (10) for some of the same kinds of tasks. They use word processing programs for (11) communication, financial software for household budgets. Individuals also use their home computers to play (12) and to communicate (13) the internet.

Small, portable PCS are (14) with people who often work away from their desks. The (15) include laptop computers, which can be (16) on the lap; notebook computers, which are about the (17) of a loose leaf notebook; and palmtop, or handheld computers, which can be operated while (18) in the hand. Laptop and notebook computers have the same (19) as desktop computers. Palmtop computers have less power but still (20) some advanced capabilities. For example, they can process household financial data.

14（）

A.satisfied 

B.helpful 

C.welcomed 

D.popular
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