Ответ:

1. he is going to buy a car.

he isn't going to buy a car.

is he going to buy a car?

2. they are going to paint the house.

they aren't going to paint the house.

are they going to paint the house?

3. we are going to bed.

we aren't going to bed.

are we going to bed?

4. it is going to be rain.

it isn't going to be rain.

is it going to be rain?

5. she is going to have a bath.

she isn't going to have a bath.

is she going to have a bath?

6. you are going to play the piano.

you aren't going to play the piano.

are you going to play the piano?

Ответ:

1)He is going to buy a car.

He is not going to buy a car.

Is he going to buy a car?

2)They are going to paint the house.

They are not going to paint the house.

ARE they going to paint the house?

3)We are going to bed.

We are not going to bed.

Are we/they going to bed?

4) It is going to rain.

It is not going to rain.

Is it going to rain?

5) She is going to has a bath.

She is not going to has a bath.

Is she going to has a bath?

6) You are going to play the piano.

You are not going to play the piano.

Are you going to play the piano?

Я не уверенна насчёт has в 5, возможно там have.