Viết lại câu: We didnt known your phone number, so we could not contact you

1.We didnt known your phone number , so we could not contact you.
=> Had ...
2.Because Simon doesnt live near his mother, he cant visit her often.
=>Were....
3.Bill never does anything if you dont tell him what to do.
=> Unless....
4.They dont have enough time so they can not do me a favour.
=>Were....