I urgently need you to revise these sentences.

1) Do you intend to start the project before Christmas?
2) I need to know which and how many students you are going to involve.
3) What do you think of our proposal of including 20 students from year 11? 4) I would be grateful to you if you let me know about these details (my queries) before the teachers' meeting, which will be held next Monday.

5) I couldn't help laughing.
I couldn't do anything but laugh.
I couldn't resist laughing.
I couldn't avoid laughing.
Are they all possible??

1) OK


2) I need to know which and how many students you are going to involve.
This sounds as if you are asking for the names of the students to be involved in the project. Yes? No?

3) What do you think of our proposal to include 20 students from year 11?

4) Please let me know about these details before the teachers' meeting, which will be held next Monday.

5) I couldn't help laughing.
I couldn't do anything but laugh.
I couldn't resist laughing.
I couldn't avoid laughing.
Are they all possible?? Yes.

Sure! Here are the revised sentences:

1) Are you planning to start the project before Christmas?
2) I would like to know which students you are planning to involve and how many of them.
3) What is your opinion on our proposal to include 20 students from year 11?
4) I would appreciate it if you could provide me with these details (my queries) before the teachers' meeting, which is scheduled for next Monday.

As for your question about the sentences related to laughter, all of them are possible and convey a similar meaning. Here they are again:

1) I couldn't help laughing.
2) I couldn't do anything but laugh.
3) I couldn't resist laughing.
4) I couldn't avoid laughing.

These sentences mean that the person had no control over their laughter and felt compelled to laugh.