A use case of the particle 的 de that I've always found odd is the way it can be added at the end of a sentence where 會/会 huì is the main verb. I've seen this explained as a form of 'emphasis', but I've never been too clear about what kind of emphasis this is. So, my basic question is: does this final 的 add anything in terms of meaning?
Let's clarify the question with some examples. If I want to say "I will go to Beijing", I think I can say this with the verb 會:
我會去北京。 - I will go to Beijing. (1a)
We can add a time adverbial so that the sentence feels more complete:
我明天會去北京。 - I will go to Beijing tomorrow. (1b)
With these sentences, I've found that it is very common to stress that the action will happen for sure by using 一定. This is a form of emphasis similar to adding adverbs like 'certainly' or 'definitely' in English:
我一定會去北京。 - I will certainly go to Beijing. (1c) 我明天一定會去北京。 - I will certainly go to Beijing tomorrow. (1d)
Now my understanding is that we can always add a final 的 with this type of 會 sentence. If this is correct, then we can say:
我會去北京的。 (2a) 我明天會去北京的 。(2b) 我一定會去北京的。 (2c) 我明天一定會去北京的。 (2d)
My questions: are these four sentences correct? Is the final 的 needed at all? Or does it change the meaning or tone of the sentence in any way?
An additional question: can we use this final 的 when 會 is used to express a skill rather than a future action? Consider the following sentence:
他會說三種語言。 - He can speak three languages. (1e)
Can we add a final 的 here?