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问题 多项选择题

可使肥厚梗阻性心脏病心前区杂音减轻的方法有（）

A.Muller动作

B.下蹲位

C.应用β受体阻滞剂

D.含服硝酸甘油

E.Valsalva动作

答案

参考答案：B, C

解析：下蹲位可使回心血量增加，应用β受体阻滞剂抑制心脏的收缩力可以减轻肥厚梗阻性心脏病的梗阻状态，从而减轻杂音。另几种选择支会减少回心血量，增加梗阻的程度，引起杂音增强。

单项选择题

The Chinese of 3,500 years ago believed that the earth was a chariot, and the sky like a curved canopy stretched above it. The canopy was nine layers thick, and it sloped slightly to the northwest, as a cataclysm had broken one of its supporting columns. This gentle slope explained the movement of the stars from east to west.

Ancient Chinese astronomy could be accurately described as _________.
A. entirely religious in nature B. based on legendary figures
C. advantages in some areas D. completely unsuccessful

According to these ancient Chinese beliefs, the sun spent the night on earth and ascended to the sky each morning from the luminous valley of the east by climbing the branches of an immensely tall sacred tree. To the Chinese people, the sun was the incarnation of goodness, beauty, and truth. In popular imagination, the sun was represented as a cock that little by little assumed human form. His battles with the dragons, which personified evil in their beliefs, accounted for the momentary disappearances of the sun that men now call eclipses. Many of the Chinese people worshiped the sun, but in the vast and complicated organization of the Chinese gods, the sun was of only secondary importance.Along with these unsophisticated beliefs about the sun, the Chinese evolved a science of astronomy based upon observation——though essentially religious——which enabled them to predict eclipses of the sun and the movements of the stars. Such predictions were based on calculations made by using a gnomon——an object whose shadow could be used as a measure, as with a sundial or simpler shadow pointers. Moreover, with the naked eye, the Chinese observed sunspot, a phenomenon not then known to their contemporaries.
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问答题

已知Cu-30%Zn合金的再结晶激活能为250kJ/mol，此合金在400℃的恒温下完成再结晶需要1h，试求此合金在390%：的恒温下完成再结晶需要多少小时。
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