分馏法原油稳定装置正常停车时，应将进料量依次按（）t/h的速度降量。
A.20~50
B.50~80
C.60~90
D.70~100
参考答案：A
It is recommended that the project ________ not be started until all the preparations have been made.
A．must
B．can
C．need
D．should
5，7，11，19，______
A．35 B．36 C．28 D．43
