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