天然气溢流关井后,天然气带压滑脱上升过程中,作用于井内各处压力()。
A.逐渐降低
B.逐渐增大
C.不变
D.突然增大
参考答案:B
---- The price is fine with me. How would you like ____ paid?
----- Well, it’s up to you.
A.this
B.that
C.it
D.one
简述胸骨的构造。