You'll have to explain what concepts you've been taught already.
To me this is a strange problem . . .
First of all, I'm not sure what "standard form" means in your course.Translate into standard form:
The only boys who deserve cake are good ones.
Answer: Some B are G . . . . . I don't agree
The statement itself is an unusual one to translate.
It says: Only good boys deserve cake.
We can translate this a number of ways:
. . "If a boy deserves cake, then he must be a good boy."
. . "A boy deserves cake only if he is good."
. . "Bad boys do not deserve cake."
It does not say: "If a boy is good, then he deserves cake."
It does not even say that there are any good boys.