根据句意，使用你所学过的介词填空，每个介词只能使用一次。

on, in, at, behind, between, next to, under

1. There are some birds ______the sky.

2. We can study this subject ______ TV.

3. Shall we meet ______ the bus stop?

4. My best friend sits ______ me. He often helps me.

5.76 is ______ 75 and 77.

6. I don't want to fall ______ others.