按要求改写下列句子，每空一词。

1. Open the door, please. (改为否定句)

    ___   _  open the door, please.

2. I can see a cup of coffee on the table. (对画线部分提问)

    ___   _  can you __   __  on the table?

3. There are thirty students on the playground. (对画线部分提问)

    How ______ ______ are there on the playground?

4. There are some birds in the tree. (改为一般疑问句)

    ___    _ there              birds in the tree?

5. They often play basketball on the playground.(对画线部分提问)

    ___   _  ______ they often __    __ basketball?