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问题 单项选择题

一个50μA的表头，内阻为1.0kΩ，把它制成一个100V的直流电压表应（）。

A.并联一个2MΩ的电阻

B.并联一个1MΩ的电阻

C.串联一个2MΩ的电阻

C.串联一个1MΩ的电阻

答案

参考答案：C

单项选择题

H1受体阻断药产生中枢抑制作用的机制是

A．阻断中枢H1受体

B．兴奋中枢胆碱受体

C．和奎尼丁样作用有关

D．和中枢抗胆碱作用有关

E．阻断中枢5-HT受体
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填空题

B Egyptian Villages 埃及村落

Most of the inhabitants live in mud-brick homes, their (1)  walls insulating against the afternoon heat. Flat roofs, exposed (2)  the northern evening breezes, serve as cool sleeping (3)  as well as storage areas. Villagers plaster the outer walls (4)  often trim them in blue, a color they believe (5)  off the evil eye. As a man becomes richer, (6)  can add a second story to his house perhaps (7)  his married son. Those villagers who have made the (8)  to Mecca paint the legend of their trip on (9)  outer walls of their homes. Such hajj houses, along (10)  the mosques, are the most distinguished buildings in a (11)

Some villagers build ornate pigeon coops close to their (12) , using the birds as food and their droppings to (13)  crops. Many houses still have dirt floors and lack (14)  or running water; women with jars balanced on their (15)  make the trek to the community well, and children donkeys haul the (16)  liquid in jerry cans.

All (17)  said, government sponsored building programs have also brought newer (18)  residences and utilities to some villages, particularly those outside (19)  Nile Valley in the Oases and the Red Sea (20)  areas.

16.（）
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