题目

  Algae(水藻) are very simple plants. They grow in fresh water or salty water. Seaweed is algae that grow in salty water. Seaweed is red or brown in color. The Japanese people use these plants from the sea in many ways. From it, they make a food called Kombu. Kombu is seaweed that has been dried, cooked and pressed together. Then it is dried again and cut into long pieces. The Japanese eat a lot of Kombu and like it very much.     Japanese farmers often use seaweed as fertilizer. It makes their plants grow better. Many farmers also find seaweed makes a fine food for their animals（2004?姜堰市）玻璃厂用卡车运进一批做玻璃用的沙子，堆成一个圆锥体，每立方米沙重1.5吨，这堆沙子重多少吨？（如图）