按要求改写下列句子，每空一词。

There are no birds in the tree.
Don't open the door, please.
They are doing their homework now.
What is he reading?
There are some boys in the classroom.

有问题可以追问哦！谢谢！
祝学习进步！！

There are some birds in the tree.(改为否定句）
There__aren't__ _any___birds in the tree.
Open the door,please.(改为否定句）
__Don't__ _open___the door,please.
They often do their homework after school.(改为现在进行时）
They__are__ __doing__their homework now.
He is reading a book.(就reading a book提问）
__What___is he__doing___?
Some boys are in the classroom.(用there be改写句子）
__There__ __are__some boys in the classroom.