减少往复泵惯性损失的方法常有()。
A.降低泵的转速
B.降低泵的吸入压力
C.加设空气室
D.采用多作用泵
E.增加泵的排量
F.提高泵的效率
参考答案:A, C, D
his play, , is very wonderful: there are many interesting characters in it.
A.out of the question
B.on the whole
C.in doubt
D.under no condition
风湿热的发病人群多为()。
A.老年人
B.中年人
C.青年人
D.儿童期
E.婴儿期