Can you make sure ______ the gold medal?

A．where Maria had put

B．where had Maria put

C．where has Maria put

D．where Maria has put

起飞落地过程中，由于坡度过大导致翼尖或发动机吊舱擦地，属于什么等级的事件？（）

A.一般差错

B.严重差错

C.一般事故征候

D.严重事故征候