Past Simple or Past Continuous1)The baby (not/sleep) when Granpa (arrive) объяснить

Past Simple or Past Continuous

1)The baby (not/sleep) when Granpa (arrive) разъяснить почему))

2)While he (travel) on the bus to work,he (remember) thet it was his wife's birthday.

3)(The children/study) while their nanny (prepare) diner?

4)While you (be) out,the postman came and (deliver) these letters.