Fill in the blanks by changing the verbs given in the brackets to passive voice.
1) Our plan __________ (consider- present continuos) by he members of the comitee.
2) The old umbrella ___________(use- past continuos) by the old man.
3) A prize ____________(give-future tense) to whoever solves this equation.
4) When the manager arrived, the problem _____________(already solve- past perfect).