Hello!

Need some help with these 3 sentences. They have to be filled with either simple future, going to future or present continuous

1. Son: Mum, what are we having for dinner tonight? Mum: I haven’t decided yet. But I think we __________(HAVE) pasta.
2. When____________you _________________(SEE) the doctor?
3. I am hungry. I_______________(GET) a sandwich.

and of course why?

How do you indicate future tense in English? Which "helping" verbs do this?

http://www.englishpage.com/verbpage/simplefuture.html

will have, are going to see and will get? correct or not?

Yes, all are correct.

Sure, I'd be happy to help you with those sentences! Let's fill in the blanks using the appropriate tense.

1. Son: Mum, what are we having for dinner tonight? Mum: I haven't decided yet. But I think we are going to have pasta.
Explanation: In this sentence, we use the "going to" future tense because Mum is talking about her intention or plan for the future. She hasn't made a final decision, but she is expressing her current intention or expectation that they will have pasta for dinner.

2. When are you going to see the doctor?
Explanation: In this sentence, we use the "going to" future tense to talk about a future event that has been planned or arranged. The question asks about the time of seeing the doctor, implying that there is a plan for that visit.

3. I am hungry. I am going to get a sandwich.
Explanation: In this sentence, we use the "going to" future tense to express a future action that has already been decided or planned. The speaker is expressing their intention to get a sandwich to address their hunger.

Please note that while the present continuous tense could also be used in some of these sentences, the "going to" future tense is more appropriate given the context of intention or expectation for future actions.