Steel is much heavier than water.
钢铁比水重多了。
But a big steel ship floats on the sea.
可大铁船，却稳稳浮在海上。
The ship is not a solid block of steel.
船不是一块实心的铁疙瘩。
Its big belly is empty and full of air.
它肚子大大的，里面全是空气。
It pushes a lot of water out of the way.
它把好多好多水，挤到了旁边。
The pushed water weighs as much as the ship.
被挤开的水，和船一样重。
When the water holds it up, the ship stays afloat.
水的力气一托住，船就浮起来啦。
