Everybody needs water. Everything needs water. We use water to wash the bowls(碗), clothes and ourselves. We use water to plant trees, flowers and crops(庄稼). Where does all water come from? It comes from clouds.

    Some of rain goes into the ground. Many people get it under the ground. Some rain water goes into the hills. It runs into lakes and rivers. Many people get it there.

选词填空。

奥秘   神秘

对____的月球，人类还将继续探索下去。

古往今来，为了探索月球的____，人类付出了巨大的努力。

我们党、我们国家生存发展的政治保证是（  ）

依据如图所示的“处在磁场中的通电金属棒在导轨上运动”这一实验现象及相应规律设计的家用电器是（   ）