It has no colour or shape. It has no smell or taste. We cannot see it, but we can feel it. It is everywhere.
它没有颜色和形状。它没有气味和味道。我们看不见，摸不着。它无处不在。
It is important to all people. It is also important to animals and plants. We all need it to keep us alive.
它对所有的人来说都很重要。它对动植物而言也很重要。我们都需要它来维持生命。
Look at the kite and the balloon. Look at the plane and the bird. They all need it too. It keeps them high in the sky.
看风筝和气球。看飞机和鸟。他们也都需要它。它使它们能飞在高空中。
What is it?
它是什么？