题目

Wang Fei，a Chinese student，and Mary，an American student studying Chinese in China，were in a supermarket. They saw a young man walking down the stairs. In his hurry，he missed the last two steps and fell onto the ground. He tried to stand up while people around him laughed. Luckily，he seemed to b e OK. http://w w w.xk b1. com Mary found Wang Fei smiling a little and was not happy about it.“Tell me，Fei，how                                                                                      c飞机机翼的防振颤装置是模仿 （ ）A.飞鸟的翅膀 B.蝙蝠的回声定位C.蜻蜓翅末端上方的翅痣 D.苍蝇体内的平衡棒