一群小伙伴来到沙滩上玩沙子。“谁知道沙子的下面是什么?”西西突发奇想。他们决定挖下去看一看。他们把沙坑挖得好深。“喂,沙子下面是什么东西?”“还是沙子。”大家请来挖沙工程队帮忙。“叔叔,沙子下面是什么东西呢?”“是淤泥。”“我们对付不了淤泥,你们请挖井队帮忙吧!”挖井队赶来了。“报告!淤泥四周渗出很多水。”一个挖井队员向 A group of friends come to the beach to play sand. “Who knows what is under the sand? ” West suddenly whim. They decided to dig down and take a look. They dug deep bunkers. “Hello, what is the following sand??” “Or sand. ” Everyone invited to dig sand engineering team to help. “Uncle, what is the following sand?” “” Is the silt. “” We can not deal with the silt, you dig well team to help! “ ”Report! A lot of water seeps around the silt."