'Will' or 'to be going to'

Look at the sky, I think it is going to rain.

Look at the sky, I think it will be raining.

Look at the sky, I think it is go to rain.

I will to go to the cinema tonight.

I will go to the cinema tonight.

I'm going to go to the cinema tonight.

I'm going to go on holiday next week.

I'm going go on holiday next week.

I will to go on holiday next week.

I will go on holiday next week.

Just a moment. I am going to help you with the bags.

Just a moment. I  will to help you with the bags.

Just a moment. I  will help you with the bags. 

A: Did you remember to buy the tickets?  

B: Oh no, I forgot! I will buy them online now.

A: Did you remember to buy the tickets?  

B: Oh no, I forgot! I'm going to buy them online now.

A: Did you remember to buy the tickets?  

B: Oh no, I forgot! I'm going buy them online now.

They will arrive at about 4 in the afternoon. 

They will to arrive at about 4 in the afternoon.

They are going to arrive at about 4 in the afternoon.

We are going have a barbecue tomorrow. It's all planned, so I hope it won't rain.

We will have a barbecue tomorrow. It's all planned, so I hope it won't rain.

We are going to have a barbecue tomorrow. It's all planned, so I hope it won't rain.

They are going to buy a new computer. 

They are going buy a new computer. 

They will to buy a new computer. 

They will buy a new computer. 

As soon as the weather clears up, we will walk  down to the beach and go swimming.

A: Coffee or tea?

B: I am going to have coffee, please.

A: Coffee or tea?

B: I will have coffee, please.

As soon as the weather clears up, we will to walk  down to the beach and go swimming.

I will do my homework this evening.

It's so cloudy! I think it's going rain.

It's so cloudy! I think it's going to rain.

I'm going to do my homework this evening.