氨气气动截止阀A/B自动关闭条件?
参考答案:
(1)A/B反应器进口温度≤286℃;
(2)MFT动作;
(3)氨喷射系统A/B氨气/空气体积百分比≥14%。
—Is it _______ English dictionary?
—Yes, and it is _______ useful one. [ ]
A. a; a
B. a; an
C. an; a
D. an; an