Question

---How long have you ______ the football team of the school?

---About two years.

1. A.
   been on
2. B.
   been at
3. C.
   joined
4. D.
   played

Answer 1

A
how long多与完成时态连用，选项中只有A、B两项合适。“成为……的一员”，用on。