题目

One morning I wasted nearly an hour watching a tiny ant carry a huge feather．Several times, it   36    several obstacles in its path．And after a momentary pause it would make the necessary detour （绕道）．  37   one point, the ant had to cross a crack about 10mm wide．After some   38    thoughts, the ant laid the feather over the crack, walked   39   it and picked the feather up on the other side, then continued on its way．I was   40   by the cleverness of this ant．It was only a small insect, lacking in   41   yet equipped with a brain to reason, explore为了探究声音产生的原因,小明和小华一起做了几个实验：小明把手放在喉咙处,大声讲话,感觉喉头振动了;小华把发声的音叉放在水中,可以激起水花。(1)通过对上面的种种实验现象的分析,你能得出的结论是：__________。(2)小华同学用手使劲敲桌子,发出很大的响声,但是他看到桌子几乎没有振动,为了使看到的实验现象更明显,你的改进方法是：____________。 发声体在振动 在桌面上放置塑料泡沫或乒乓球等 【解析】 (1)讲话是声带的振动，音叉发声使水振动，都能证明声音是由于物体振动产生的。(2)桌子是较大的物体，发声振动不易观察，可转换成桌面上小纸屑的振动，所以可在桌子上放一些塑料泡沫或乒乓球等。