题目

   Mrs. Blances’ husband went off on a business trip to America. He planned to leave New York for Washington. He wanted to catch the 4:00p.m.plane to Washington. It was seven o’clock in the afternoon. Mrs. Blanches received a telephone call from her husband. He told her that he was still at the New York airport. Mrs. Blanches was so surprised and asked him what happened. “What happened, honey?” asked Mrs. Blanches. “Well,” said Mr. Blanches. “I really don’t know what happened, honey. Everything was going fine. At half past three, I got my air ticket, checked my luggag1．如图所示，两个质量相等的物体沿同一高度、倾角不同的两光滑固定斜面顶端从静止自由下滑，到达斜面底端．（　　）A．到达底端时的动量大小相同B．下滑的过程中重力的冲量相同C．下滑的过程中弹力的冲量相同D．下滑的过程中合外力的冲量大小相同