What does "Sour grapes" is such an intersting idiom, but I can't fully comprehend it. Could you please explain?
I would appreciate it so much:) mean?

See a translation

Утро доброе, Марко:)

To be frank, I've already gotten the answers from friendly Brits so I should have removed this question from the list:(
However, you know I adore you and, hopefully, it didn't take you long:)

I would like to know if "this" is the only right option or you could have said "or is it/that case of four grapes..."

@marko_212 Yes, it's written more than naturally:)

@marko_212 no, I replied to "Я надеюсь, что это было полезно"

@marko_212 На самом деле, лучше сказать "доброе утро" либо же "с добрым утром". "Утро доброе" is kind of playing with words, you can hear it once in a while in one's speech. I didn't mean to baffle you:(

It's a very interesting question:) I will do my best trying to explain. This verb is often left out in Russian, you say:

● He is a good singer.
● Он является хорошим певцом.

It would be a word-to-word/literal translation, but in 8 out of 10 cases we don't say "являться" (the infinitive).

● Mike Tyson is one of the most prominenrt boxers of all times.
● Майк Тайсон является одним из самых выдающихся бойцов всех времен / Майк Тайсон - один из самых выдающихся бойцов всех времен.

Both options are correct and might be implemented in your essay, for example. A couple of more sentences:

● Земля является нашим домом, мы обязаны беречь окружающую среду / Земля - наш дом, мы обязаны беречь окружающую среду
● Earth is our home, we must protect the environment.

Basically, являться = быть, служить чем-нибудь (serve as smth):

● Его поступок является очередным доказательством нашей дружбы
● His act is another proof of our friendship

The takeaway: the longer a sentence the higher a chance that "являться" will be used.

you know English better than Vlad from Russia 😂. As far as I'm concerned we cannot say in English "he didn't seem in court", only "appear/show up", right? If yes, then "seem" doesn't fit here

@marko_212 "to seem" = казаться

@marko_212 I have to go away for 15 mins, I'll make up some sentences to show how the word "казаться" is used

Thanks, Marko, I know they can be equal, but in some cases they're not, are they?

Ex:
● He seems to think he's the best here - correct
● He appers to think he's the best here - not quite correct, but still it's no big mistake, is it?

We cannot see the process of his "thinking", so it's better to use "seem". At least, I hope so:)

@marko_212 крепких снов:)