油管的作用有哪些?
参考答案:
(1)将地层产出的油气水从井底输送到井口;
(2)压井、洗井、酸化呀裂等井下作业都要通过油管进行;
(3)油管在采气过程中被腐蚀和磨损,方便更换。
某人受伤,如果血液缓慢渗出,颜色暗红,则受伤破裂的血是______;如果血流出,颜色鲜红,则受伤破裂的血管是______.
You should ________ the whole affair, but don't judge it only by your experience.[ ]
A. analyze
B. resemble
C. concentrate
D. substitute