一种儿童玩具—陀螺(如下图)，上面是圆柱，下面是圆锥。圆柱的直径是6厘米，高是8厘米，圆锥的高是圆柱的高的 $\frac{3}{4}$ ，这个陀螺的体积是多少立方厘米?(保留整立方厘米)

We all know the air____us____．____makes the air dirty and it makes us unhealthy．Rubbish makes the land and water dirty．The dirty land and water makes us unhealthy and ____too．Trees make the____ ____and beautiful．Trees also give us delicious fruit and useful____．We should keep the air clean and ____throwing rubbish into rivers, lakes or seas．We should plant ____trees．