Choosing the correct sentence. One sentence has a mistake. Which is the correct sentence? Put “+” and “-”.

1
a Is going to rain.
b It’s going to rain.
2
a Do you wash your hair this evening?
b Are you going to wash your hair this evening?
3
a She’s going to have a baby.
b She’s going to has a baby.
4
a Are they many students in your class?
b Are there many students in your class?
5
a I’m going to the Post Office to buy some stamps.
b I’m going to the Post Office for buy some stamps.
6
a Every evening I go home and I listen to music.
b Every evening I’m go home and I listen to music.
7
a They waited for me in the garden.
b They waited for my in the garden.
8
a He can’t answer the phone because he’s having a bath.
b He can’t answer the phone because he has a bath.