"You are a big help for me."
Translation:Vi estas granda helpo por mi.
Certainly in (British) English it is more usual to say, "You are a great help to me." Duolingo accepts "to me" when the Esperanto sentence is presented for translation into English.
No. Verbing roots gets you "to perform an action related to the root".
It is only a computer which knows nothing about languages. Every correct answer has to be programmed by hand. Just report it as a possible answer and it might be added to the database.
How do you report "helpego" as a possible answer? I thought that this is where to report it.
No, this is the discussion forum. To suggest an alternative answer, you need to hit the flag icon.
No. After a preposition it's not accusative unless there's movement. ("on" vs "onto" for example)
Here, there is no direct object. "to be/esti" is a stative verb that equates/compares "you" and "a big help".
"To be/esti" is a stative verb, which means transitivity doesn't even apply. So it would be helpego, not helpegon.
In a noun phrase, the adjectives must be declined the same way as the noun. If the noun takes the plural -j, the adjectives take the plural -j. If the noun takes the accusative -n, the adjectives take the accusative -n.
So you have two things wrong: First, "granda" and "helpon" are not declined in the same way. Second, the verb "esti" does not assign the accusative. It's a stative verb, not an active verb. What follows is not a direct object but a subject complement.
The correct answer is "Vi estas granda helpo por mi."