[quote="Shuntang, in reply to Metal56, who told him "It can rain soon" is not an English sentence,"]Nevertheless, I didn't know "It can rain soon", though awkward, is an ungrammatical sentence, in your recognition.[/quote]
Shun....

M56 told you this is not an English sentence
not because it is ungrammatical, which it is, strictly speaking from a technical point-of-view, even, as you admit, it is decidedly awkward. He told you it is not an English sentence because no English speaker who knew what they were doing would ever utter it. M56, and I, and every other native speaker out there who might, for whatever odd reason might be reading this twisted conversation, simply cannot figure out what that sentence could possibly mean. It just does not compute in the brain. It leaves us breathless in confusion about the possibilities, given what we
do understand about the grammar, and the array of imaginable interpretations for the words used in its construction. It is among the millions of "possible" English constructions that follow the "rules" of grammar as put forth in textbooks and coursebooks, which simply do not exist in the entire corpus of English language use, because they just do not make any kind of sense at all.
You have every right to believe that English has a future tense, if you want to. But you have most definitely not proved it...you have not gone anywhere near a proof. You are among a diminishing set of "rule" appliers who insist on insisting that it must be true because it's there in the (old and very much outdated) books. An extremely small minority of linguists will agree with you, as by far the majority of them do
not believe as you do.
It's all right for you to come here and say that you believe in future tense. It is not OK for you to type out some long issue of gobbaldygook, and then claim you have proved your case. No one here is buying that cr*p. It is certainly not a way to make friends around here, as you can plainly see, whether you're English, Dutch, French, Spanish, or Chinese (or whatever else). If you don't get some academic manners, your ideas will continue to be rejected out-of-hand. No one will take you seriously.
Larry Latham