根据答句,用合适的疑问词或词组补全对话
_______is the poster about?
About our Earth.
_______modules are there in the book?
There are five.
_______can you stop the sandstrom?
We can plant trees to stop the sandstrom.
_______can I find these photos?
In this book.
_______are trees  important to us?
Because they provide us with a lot of things.