Will, Be going to. What are you supposed to say when you use each one?

Good morning, Mimyo. Nihonjin desuka.

You don't have to apologise for your language, especially now that you're in Canada. As you saw, even many native speakers don't consciously understand these types of differences.

You've got the basics down,

"
Basically, I thought,
'Will' -> predicts, plans and etc, but not intended or you are not sure what will happen in the future.

'Be going to' -> same as will, but strongly intended or you have a clear plan to do something,"

but think of the two on a scale, where 'will' represents one end and 'be going to' the other. For some situations, either can be used, this is where they meet in the middle of the scale.

Example:
I'll be going to Tokyo on Friday. [decided but the speaker can use 'will', a 'will' of more polite]

I'm going to go to Tokyo on Friday.

OR

I'm going to Tokyo on Friday. [present continuous/progressive for the future]

For some situations, 'will' cannot be used. Imagine a man walking along the street, not paying attention, towards an open manhole.

Seeing this, a native speaker would only use 'be going to', as in

He's going to fall in the hole.

Neither 'will' or the present continuous for the future [PCftF] are available for this situation.

But a general comment about the open manhole with no specific situation present, ie. no man about to fall in, could see the use of 'will'.

Mimyo: [to friend] People will fall in here if they don't put up a guard.

OR a more concerned, serious,

Mimyo: [to friend] People are going to fall in here if they don't put up a guard.


The PCftF can't be used here either, as it's used for relatively near planned events.

Remember that there are lots of situations where either could/can be used, so just because you expect one to be used, a speaker might choose to use the other. Even where it seems 'be going to' is the more natural choice, some will choose 'will' because it is more formal/more polite.

Ganbatte!

If you have any other questions or if I haven't explained this well enough for you please feel free to ask further.

The simplest rule (really just a simplification of what JTT posted) for this is to use "will" when you have decided something at the moment, and "going to" when it was previously decided.

While there is some validity in that, Robert, I think it holds for some situations more than others.

"I'm gonna go get pizza and beer."

Just decided, and 'will' could also be used but I think BGT shows a firmer resolve.

Yeah, like I said it's a simplification. But it's one that ESL students find useful in my experience because both ways of saying it have exceptions.

For example, someone might jokingly say "I'm gonna kill you!" without any such resolve and "I will kill you!" is more rarely used (by my estimate). Both ways of explaining it will have a lot of exceptions.

BGT - be going to

I think mine and Robert's comments help illustrate the complexity of language. I said that BGT shows greater resolve and I think it might, though the speaker certainly could have chosen to use 'will'.

'I'll go get some pizza and beer."

This sounds more to me like a suggestion though it could be that the decision is as strong in the speaker's mind [politeness override?]

And a reply, using 'will' could also show resolve;

"Pizza and beer, pizza and beer, I will not eat that crap again tonight."

To Mimyo: What you must understand from all this is that modal verbs/semi-modal verbs like 'will' and 'be going to' have many nuancial meanings and humans can have many different and variant thoughts which all need to be expressed.

So what you might expect to hear in a given situation could be a reflection of feelings other than what the general guidelines suggest. Listen to conversations around you and if you hear something that seems strange try to think from the context what those differences might be.

You've probably been taught that 'will' is the future tense in English. It is NOT. English does not have a future tense. We have multiple ways to show a future sense in English.

The modal 'will' has a number of meanings, 7, 8, whatever, and these don't all relate to a future, though there is an element of it in there.

Agreed, Robert, it does.

I think the use of BGT in "I'm gonna kill you" is intended to imply resolve, though not actual intent; something 'will' can't show in this particular situation, possibly because of its first mention --> tentative feeling.

I appreciate for your kindness, JTT and Robert Gentel.
It is very helpful for me to understand more about learning English.
I believe that learning any kind of languages might be difficult if I just try to focus on the grammar.

Especially what JTT said really impressed.

I would like to try to just feel and get accustomed to what English speakers usually say in a daily life.

Again,
Thank you, JTT and Robert Gentel, for giving me the clear guide line to learn English.