如图表示先天性行为与学习行为的相同点和不同点，其中阴影部分表示相同点．下列哪一项可以写在阴影部分（）

空气是否传声的实验中，先让电铃发声并放入玻璃罩内，____，发现电铃的声音将逐渐____（填“变大”或“变小”），然后把空气____ ，会发现声音将逐渐____（填“变大”或“变小”），这个实验表明：玻璃罩内的空气越稀薄，传出的声音____，如果没有空气，声音就____（填“能”或“不能”）传出。也就是说真空____传声。

    Two men walked through the countryside toward another village. As they come to the edge of a river, they saw an old woman sitting there upset because the bridge was____by the storm, and she was too weak to walk across the stream. The first man said____, “We are tall enough, and we can carry you across” The second man thought it troublesome, but he agreed reluctantly（不情愿地）. So the two men ____ the bridge, lifted her between them and carried her across the river. When they got to the other side, they set her down and she went on her way gratefully. After they had walked another mile or so, the second man began to complain “My back began to hurt for lifting her.” The first man ____ smiled and nodded without a word.