Before I even attempt to say anything about the question, I am red flagging this sentence: |We will always attribute on the usage of grammar|. That sentence is written by a non-native speaker, so I really am not going to tire myself out, I'm afraid.

Not only that, @Lambie. Everything's wrong there: change of FROM, you undoubtedly KNEW. Not to mention the content itself...

I understand that this slid has style or even grammatical mistakes, but to the point, Are these things correct?

We don't use the term "indefinite" but "simple". Also, it's not true that the tense always expresses the time of the action: "tense" is a grammatical term, "time" is a logical concept. In If only I knew the answer, "knew" is past tense but refers to the present time.

I'll answer it, COX1. I think it is correct: 3 tenses and 4 forms sounds correct to me, although some pedants on here would argue that English has no future tense, but that is just mere pedantry.

Actually, "knew" is past subjunctive in that example and therefore not a tense, but a mood. Its past tense equivalent is also "knew", so they look the same thing, but it's in the past subjunctive there.

Verbs have tense AND mood. Take this other example: When you come tomorrow, remember to bring the grammar book. "come" is present tense but expresses future time.

That one is correct and this situation of "come" exists because English did not have a true future tense in Old English and still doesn't today. We still use verbal constructions every day that look like the present, but act as the future since English has no "true" future tense: "I'm doing it tomorrow" to mean "I shall do it tomorrow."

I found such method of learning also here: slideplayer.com/slide/5919536 in slides 9-10-11, but the problem that in slide 12 it states that there are no present indefinite and past indefinite. So it contradicts itself apparently.

One thing is clear, @COX1. That site is not reliable. Look for a better one.

Actually, I know what it's trying to say. It isn't showing a specific verb, Cox1; it's showing you all of the constructions possible for any verb. If it had picked a random verb out like "to write", the present indefinite would be "write" or "writes" depending upon the person, i.e. "I write", but "he writes". The past indefinite would be "wrote" for all persons.

It thinks you understand what the simple present and simple past are, which are also called the present indefinite and past indefinite respectively; it just wants to show you the constructions of the other forms. The future perfect continuous then of "to write" would be "shall have written" or "will have written", i.e. "I shall have written" or "he will have written."

@NicholasCastagnola Very nice explanations, thank you for the patience! ^ I understand that is generally correct to say that each tense has 4 forms but it depends on the verb. And this table in the presentation is talking specifically about the auxiliary verbs.

You're welcome. I've looked at the slides and that's what they are trying to say. The creator assumes you know that those two forms will change depending upon the verb that you may use; he just wants to show you how to construct everything else because those constructions never change for any verb.

Yes, the auxiliary verbs are "auxiliary" or "helping" verbs; therefore, they don't have an indefinite form. Many of them used to have indefinite forms in Old English, but not anymore. "shall" had an indefinite form in Early Modern English: "He to England shall along with you." —William Shakespeare. This form of "shall" meant "will go".

Right. Sometimes they are auxiliary verbs and sometimes just lexical verbs (capular verbs). By the way, when I studied grammar I've been told that "shall" is the correct form for 1st person singular or plural (I shall and we shall).

I believe it has a future tense, too, but people say it's a misnomer---that because there is no future form of the verb and only a construction, there is no future "tense". The definition of "tense" often calls for a verbal "conjugation" rather than construction. And yes, Cox1, you are correct about "shall"; however, few people actually follow the rule. Often "will" is used for first person, so don't always be lulled by that bookish rule. Also, it's copular verbs---not capular, which doesn't exist.

The whole proposition sounds completely illiterate to me. A native speaker should be able to actually understand an explanation. It's completely confusing. Not worth tackling.

@Nick I agree with almost everything you said in this thread but wanted to point out that "will have written" is just future perfect. Future perfect continuous would be "will have been writing."

You are correct. That was an error from my typing fastly. I know that it is not the future perfect continuous. I should have reread my post. Merry Christmas!