石油天然气站内工艺管线工程，管端与平焊法兰密封面的距离应为管子壁厚加（）。
A.0mm
B.1mm
C.3mm
D.10mm
参考答案：C
根据语境，写出适当的答语或问句。
1.—Excuse me,Betty.Could you help me,please?
— _____.Is this big box?
2.—_____ your watch?
—I think it is broken.
3.— Thank you very much.
— _____.
4.—_____?
—It's a quarter to twelve.
5.— _____ to drink?
—Yes.I'd like a glass of orange juice.
机械通气导致通气不足的原因有（）。
A.潮气量设定不足
B.管道漏气
C.吸呼比不合适
D.机械死腔过大
E.呼吸道梗阻
