Help meeeee 1,Why don't we donate old books to street children? => I think we 2,When did you start taking part in the aerobic club? => How long

1. I think we should donate old books to street children.
( Why don't we + V = I think we should + V )
2. How long have you took part in the aerobic club?
( Cấu trúc: When did S start + V-ing? = How long have S + P2?)

`1.` I think we should donate old books to street children.

`->` S `+` Should `+` V : Nên làm gì...

`2.` How long have you been taking part in the aerobic club `?`

`->` How long `+` have/has `+` S `+` been `+` Ving `?`