往复压缩机的排出工作过程是在活塞缸容积不断减小，直到活塞缸内压力高于出口管中压力时而推开排出气阀不断将气体排出出口管中的过程。
参考答案：对
女，38岁，突然咯血2小时，红色鲜血，可见血块。查体BP132/80mmHg，双肺呼吸音清，未闻及啰音。HR89次／分，未闻及杂音。胸片未见异常。应当首先进行的是（）
A.痰找结核菌
B.行纤维支气管镜检查
C.判断是否是上呼吸道出血
D.肺通气灌注扫描
E.胸部CT
An analyst does research about probabilities of a fund and an index. The fund underperforms the index, given the index return is positive is 0.45. The fund underperforms the index and the index return is positive is 0.20. If the two events "the fund underperforms the index" and "the index return is positive" are independent, the probability that the fund underperforms the index or the index return is positive is closest to:（）
A. 0.44
B. 0.69
C. 0.89
