Глагол в правильной форме1) I (to wait) for him since 2

Глагол в правильной форме
1) I (to wait) for him since 2 p.m.
2) They (to have) dinner when the phone (to ring)
3) Our schoolchildren (to take part) in the conference last year
4) The president (to elect) for the period of 4 years
5) He (to return) bythe time we are here
6) She said they (to be) hungry after their trip yesterday
7) The form (to fill) by them was done in the wrong way