855-09-03

3. The National Transportation Safty BOard has recommended the use of fail-safe mechanisms on airliner argo door latches (ssuring the doors are properly)closed before takeoff and  to  prevent them from popping open in flight.

D) to assuring closing the doors properly

E) to assuring that the doors are properly closed

答案是E  我想請問一下 D錯在哪裡  謝謝