管段吹扫
参考答案:
用气体吹扫清除管段内的杂物。
In January, 2004, the United States successfully launched “Spirit”, a Mars Exploration Rover, _____ a new milestone in the history of mankind.
A.it marked
B.marking
C.marked
D.to mark
洋地黄类药物的使用禁忌证是
A.心房颤动B.心房扑动C.充血性心力衰竭D.室上性心动过速E.三度房室传导阻滞