下图为热力作用形成的等压面分布示意图，图中①至④点的气压，由高到低排列顺序正确的

中东地区在亚洲的_________部和非洲的_________部。

在施工现场制作玻璃钢弯头时，均采用热弯。

对既有铣面又有镗孔的工件，一般先铣面后镗孔。

超高压锅炉的冷态启动升温速度不应超过（）℃/min。

A.10

B.5

C.2.5

D.2

The operating cord on an inflatable liferaft should be renewed by（）.

A.removing the top half of the shell，cutting the line at its source，and renewing completely

B.cutting the line where it enters the case and replacing that portion

C.leaving the original line and tying another one to it so the two lines will take the strain

D.an approved servicing facility ashore