This English sentence might be perceived as requesting a scientific explanation of flower growth, rather than a statement of the quality of their growth. "How are the flowers growing?" would be preferred.
If the Russian could mean either, why is one translation to be preferred over the other? I indeed understood it as a question (e.g. from a child) about how flowers grow, and translated it accordingly. The: "How are they doing?" aspect never occurred to me (although I concede it should not be marked wrong).
If we phrase the English "How do the flowers grow?" then it can also take either meaning, if that's desired. On the other hand, that choice of phrasing might be unlikely in both cases.
Какрас тут цветы. Was what I heard. Translates to "finally there are flowers here."
The singular for "flower" seems to be цветок, which would make чветы an irregular plural.
Genitive is цветка
Those follow the declension table for a masculine stem of цветк-, which is probably normal usage, dropping the "o" from цветок.
So, a "normal" nominative plural would be цветки (Russian spelling rules change -ы to -и after к), but the "k" is dropped in the plural stem. In checking other cases, the "k" is also dropped for plurals in other cases., e.g., plural dative is цветам.
That is indeed the case. "Цветы" is an irregular plural. "Цветки" is understandable, but sounds distinctly odd.
No, because that is not a correctly formed question in English. You have to ask: "How do they grow?", not: "How they grow?" It could also be: "How are they growing?", but it needs a helping verb of some kind.
I agree, but How flowers grow? is accepted now. And I don't know why. Maybe in modern American colloquial language "do" isn't necessarily. Anymore.
That sounds just wrong to me. :( If a foreigner asked me to correct their English, I would correct it. "How flowers grow?" sounds like a cute attempt by someone who really can't speak English very well.
I have heard native english speakers say things like this, but it is very rare, and they are usually very old. "How flowers grow" would be used to comment on flowers growing faster than you would have thought "oh my, how flowers grow!".
You appear to have overlooked the question mark. NO native English speaker would ask: "How flowers grow?". In this example, we're clearly dealing with a question, not an exclamation.
Maybe in modern American colloquial language "do" isn't necessarily.
necessarily → necessary.
"Necessarily" is strictly an adverb while "necessary" is an adjective. This sentence calls for an adjective. (You may be confused by the fact that in Russian the short neuter form of adjective "необходимо" coincides with the adverb, but you can always check yourself even in Russian by changing the subject -- even implicit "это" -- to something explicitly masculine or feminine: эта запятая здесь необходима.)
P.S. As for the subject matter, I completely agree with Tina_in_Bristol: as as a stand-alone question "How flowers grow?" is simply wrong. It can only work as a part of a bigger sentence:
Would you like to know how flowers grow?