be going/ready/good. What structure are these?

[Bambook]

Hello to everyone. Please comment my points below.
A. Be going.
B. Be ready.
C. Be good.
1. I hope those are correct English sentences so only then the points below make sense.
2. "Be" - main verb (not auxiliary).
3. "Going/ready/good" - adjectives.
4. Are the sentences of PRESENT SIMPLE structure?
5. How to turn them into questions?
5.1. Only "Are you ready?" coming to my mind. But that is NOT PRESENT SIMPLE.
6. How to turn them into negatives?

D. Go fast.
7. Here I have no problem. "Do you go fast?", "Do not go fast". Though "fast" here is an averb and not an adjective.
8. Are A, B, C sentences of absolutelly same structure as D?

 

[Tarheel]

Say:

How can I turn them into questions?

Say:

Only "Are you ready?" comes to mind.

"Go fast" can be a sentence itself.

 

[Piscean]

A. Be going.

That's unnatural. we'd be more likely to say;

Get going.
Be on your way.
Go!

In each case, the verb is imperative. This is not a tense.

B. Be ready.
C. Be good.

Once again, the verb-forms are imperative.

You can make each of them a negative command by putting Don't before the verb.

You cannot have an interrogative imperative.

 

[Bambook]

Once again, the verb-forms are imperative.

Imperative, I understand as a command verb, then it is clear. And that is exactly why I thought they are Present Simple
Because I saw in the books that Present Simple is used to give commads (one of the usages). Like: Stand still. Think well. Is that correct?
That is why I thought that all my sentences were also the same Present Simple. Not?

Don't before the verb.

Do not be ready. Do not be good. Like that? Oh indeed so easy. But again, they look like Present Simple to me.

you canny have an interrogative imperative.

Do you mean to say "You can not have an interrogative imperative"? Than it makes things easier. Because in Russian same logics.
"Canny" was difficult because this dictionary did not give such meaning "https://dictionary.cambridge.org/dictionary/english/canny"

 

[Piscean]

Because I saw in the books that Present Simple is used to give commads (one of the usages). Like: Stand still. Think well.

The present simple is not used to give commands. In which books did you read this?
The forms I have underlined are imperative.
Think well is not natural. We'd probably express the thought by Think carefully.

 

[Piscean]

"Canny" was difficult because this dictionary did not give such meaning "https://dictionary.cambridge.org/dictionary/english/canny"

That was a typo, now corrected. Sorry.

 

[Bambook]

The present simple is not used to give commands. In which books did you read this?
The forms I have underlined are imperative.
Think well is not natural. We'd probably express the thought by Think carefully.

Which book? I could not find at once. If I find I will write here. I also checked "English Grammar in Use" by Raymond G. Murphy (blue), and thanks god it was not that. So my the most basic pillars of English Grammar staid unshaken . Though your telling "The present simple is not used to give commands" brough some disturbance to my orderly arranged knowledge.
So the issue is now clarified for me. Thank you, it was fruitful information!

 

[emsr2d2]

Which book? I could not find at once can't find it at the moment. If I find it, I will write post the information here.
I also checked "English Grammar in Use" by Raymond G. Murphy (blue) no comma here and, thanks thank god, it was not that. So my the most basic pillars of English grammar staid remain unshaken.
Though However, your telling saying "The present simple is not used to give commands" brought some disturbance to my orderly arranged knowledge something I thought I knew for certain.
So The issue is has now been clarified for me. Thank you. It was fruitful useful information!