Just one more thing.

Which of the following sentences are grammatical?
Thank you very much for your cooperation.

1.I spent most of my holiday at home.
2. I spent the greatest part of my holiday at home.
3. I mainly/mostly stayed at home during my holiday.
4.For the most part, I spent my holiday at home.
5. Could you tell me what the weather will be like tomorrow?

All of them look grammatically correct to me.

For 3, both mainly and mostly work, but mostly is a better word for what you are trying to say.

To determine which of the following sentences are grammatical, we can analyze each sentence individually. Here are the explanations for each sentence:

1. "I spent most of my holiday at home." - This sentence is grammatically correct. It is a simple statement saying that the majority of the person's holiday was spent at home.

2. "I spent the greatest part of my holiday at home." - This sentence is also grammatically correct. It has a similar meaning to the first sentence, but uses the phrase "greatest part" instead of "most".

3. "I mainly/mostly stayed at home during my holiday." - Both versions using "mainly" or "mostly" are grammatically correct. They indicate that staying at home was the primary activity during the person's holiday.

4. "For the most part, I spent my holiday at home." - This sentence is grammatically correct. It uses the phrase "for the most part" to indicate that the person spent a significant portion of their holiday at home, but not necessarily the entire time.

5. "Could you tell me what the weather will be like tomorrow?" - This sentence is also grammatically correct. It is a polite request asking for information about the weather forecast for the next day.

Therefore, all of the given sentences are grammatical.