I think that now you have 2 excellent answers!

Past-tense verbs express something unreal: 'It's time we left. Our son will come to visit us and noboday at home now . 'I wish I were younger, I would be able to run fast. ' 'If only I lost some weight , I would be able to dress this shirt.' = The past simple expresses something unreal in the present, something that is not so. 'Suppose we were rich.' (We aren't rich.) 'Imagine you wanted to murder someone.' (You don't want to.) However, After 'suppose', 'supposing' or 'if' we can use either the present or the past for a possible future action. 'Suppose/Supposing something goes/went wrong, what then?' 'What if you don't/didn't have enough money to get home?'

hi friend...i can answer (wish -meanings): wish expresses several related ideas.... you can notice the verb forms which follow wish : 1- a regret for something in the past that is to late to change: ex: i wish i (had taken )her advice .(had +p.p). 2- frustrating with your current sitation, which could change : ex: i wish i (could) pass my driving test i 've tried several times and i keep failing. 3- dissatisfaction with your current situation , which cann't possibly change : ex: iam tired of behaving in an adult way, i wish i (were )ateenager again . note this : i wish( you would )be quiet when you come in late, you woke me up last night. * you say i wish i (could)...you say i wish you ( would). i hope you get it ???!!!!.........