单项选择题
A.Apply ice-cold compress and renew every 4 hours
B.Commence artificial respiration immediately
C.Give enema
D.Pass catheter into bladder
单项选择题 A safe fuel system must（）.
单项选择题 A large vessel is equipped with a controllable pitch propeller. Which statement is TRUE?（）
单项选择题 A large valve，usually installed above the ram preventers，that forms a seal in the annular space between the pipe and wellbore or，if no pipe is present，on the wellbore itself is called the（）.