we know that trees are useful in our everday life.they ( ) u

we know that trees are useful in our everday life.they ( ) us many
we know that trees are useful in our everday life.they ( ) us many things,such as wood,oxygen,rubber,medicines and many other things.they can（ ）tell us a lot about our climate.the following are the reasons.if you( )a tree ,you can see that ir has many rings.most trees gro one new ring( ) year.because of this reason,we know( )a tree is.a tree over a hundred years old means that it has more than a hun dred( ).when the climate ids dry or very cold,the trees do not grow very much and their tings are usually( ).when it is wet and warm,the rings are much thicker.if the tings are suddenly very thin or suddenly very thick,this means that the ( )changed suddenl