the most important thing I am going to say/will say/say

[navi tasan]

Let us say I am giving a one-hour talk. I want to say this in the middle of my talk, right before I am going to say the thing I think will be the most important thing I will say in my talk. Which of the sentences should I use?

1) This is probably the most important thing I'm going to say tonight.
2) This is probably the most important thing I will say tonight.
3) This is probably the most important thing I say tonight.

 

[Tarheel]

The first one. However, try: "This is probably going to be the most important thing I say tonight."

 

[emsr2d2]

Let us Let's say I am giving a one-hour talk. I want to say this something in the middle of my talk, right before I am going to say the thing I think will be the most important thing I will say in my talk. Which of the following sentences should I use?

1) This is probably the most important thing I'm going to say tonight.
2) This is probably the most important thing I will say tonight.
3) This is probably the most important thing I say tonight.

Note my changes above. I know we regularly remind learners that we use contractions more often than not but in some cases, I'll go as far as to say "always". One of those contractions is "Let's". When you're making a suggestion of something we should do, use "Let's" not "Let us". Look at the difference between the following uses of the contracted and non-contracted forms.

"Let's" used as part of a suggestion:
Let's imagine I've won the lottery.
Let's say I'm going to buy a unicorn.
Let's picture a cloud that looks like a fish.

"Let us" used to mean "Allow us":
Please let us go to the cinema, Mum! We've been waiting for this film to come out for months.
Can you let us get on with our homework? It's got to be in in less than twelve hours.

The only exception I can think of in (relatively) everyday English is "Let us pray", said just before a group prayer. That has remained steadfastly in the non-contracted form.