Translation:He had often called me his best student.
One could think there could be an issue with translating Schüler as "student" instead of "pupil". So far I remember, DL kind of made a point of reserving "student" as a translation for Student. But I think DL doesn't take this distinction rigidly, as even they themselves used "student" in this translation.
Anyway, I have written "He had frequently called me his best pupil", but it was also not accepted.
The only remaining explanation would then be in the adverb used, but I think there is no significant difference between the meanings of "frequently" and "often" to justify it. In this discussion about this difference, someone tries to reason that "frequently" would imply some sort of regularity which would be absent from the "often", but this doesn't make sense to me. I think to imply regularity one would used "regularly" instead! But I'm neither a native speaker nor an expert. Maybe someone who is can shed some light on this topic?
Perhaps like us, they have two words. Although they are interchangeable, "häufig" is perhaps more directly used as "frequently" and as the adjective "frequent" as well. http://dictionary.reverso.net/german-english/h%C3%A4ufig
No, the particular "usage formula" (so to speak) of nennen that you quoted is not used in the sense you mentioned. The actual meaning is in the sense of mitteilen (to share), in particular to give one or more names to a person. One of the examples Pons gives for it:
Können Sie mir einen guten Anwalt nennen? (Can you give me the name of a good lawyer?)
The sense in which the verb nennen is used in the current exercise is "to name" (benennen). The structure is like this: jemanden/etwas (Akk) etwas (Akk) nennen. Some further examples from DWDS:
er hat mich gestern (laut, vor allen Leuten) einen Dummkopf genannt
das nenne ich Glück
I think you're confusing infinitive of the verb to be, "sein" with the male possessive, "sein."
"Ich bin sein bester Schüler" is nominative. BUT "bin" is the first person singular form of the verb "to be" -- that's where "sein" comes in. The reason it's nominative is that the subject and object are the same thing -- equivalent -- because one of them IS the same as the other.
See "conjugations of the verb to be, sein" at: http://german.about.com/library/verbs/blverb01.htm
Less confusingly, "Ich bin der beste Schüler" is nominative for the same reason.
"Sie hat mich ihren besten Schüler gennant." is accusative, just like "Er hatte mich seinen besten Schüler genannt." The subject, pupil, is receiving the direct action of the verb, to be called.
German word order is different. I think a pronoun object usually comes right after the conjugated verb in a main clause or simple sentence. The time frame usually comes at the beginning of the middle section which would be right after that; then, why and then how and then where.
It does state that a short adverb of time can precede a noun object. The noun object in this case is probably considered to be a part of the ending verb
Then it does go on to say that emphasis would change with different word order, so I suppose it might be possible. Wouldn't it mean that "he had OFTEN called ME his best student. (sometimes he called other people his best student)? Often me, so other times not me? I hope a native speaker comes along to explain how this word order would be interpreted. I think in the regular word order "oft" affects the verb rather than the pronoun.
There are different uses for "nennen" and some use Accusative/Accusative, especially calling someone something. Yes, "name your price" or "state your preference" takes Accusative. http://dictionary.reverso.net/german-english/nennen There is even a context for Accusative/Dative when you name a child after someone. (the preposition Nach takes jdm or Dative) http://german.about.com/od/grammar/ht/Dative-Prepositions.htm
Yes. Why would you complicate what's a pretty straightforward sentence? Especially since "nennen" is a transitive verb and takes a direct object. Actually, if you want to criticize any element of the sentence, you should take issue with DL's translating "Schueler" as "student." In German, "schueler" is--more precisely-- "pupil." "Student" is the German equivalent of "student."
No, you would not use " as", which Vaarlam did say. "as" is used to mean "like"; the person is not "like a student"; that person is a student. That would not be used in the English translation. If the teacher were saying I am like his best student, a different verb would be used. We do sometimes say "someone is voted as president" to mean "is voted for the job of president", and " I got a job as a receptionist." is also a good use of that. It is not used with the verb "call" but it is sometimes used with the verb "name" when it is used to mean "appoint". "He will be appointed as general safety inspector." I would say "He was named "Chief Engineer" and that would mean that it is done and that is what he is now, but using "as" might mean that it still needs to be approved. Scroll down past the conjunction definitions to the preposition definitions. You could say "The teacher thought of him as a good student." but that would not be a translation of this sentence. http://www.learnersdictionary.com/definition/as
For Vaarlam, in German "Student" is used to mean a University student, but in English "student" is used for any age and school and it is more commonly used in the US than "pupil". You could be six years old and be called a student in English.
its seinen because it is the object of the verb "called" and is therefore accusative masculine. I am not sure what the rule you are referring to is, but "oft" is an adverb, not an adjective, and it qualifies the verb and doesn't affect the inflection of the possessive determiner "seinen"
No, that's present perfect, not past perfect; it would be "Er hat mich oft...," not "Er hatte mich oft..."
It means the action is relevant to the present. You're still his best pupil, and he might call you his best pupil again.
"He had often called me his best pupil," is all in the past. Maybe he's dead, maybe he no longer talks about you, maybe you're not his best pupil anymore.
LukeH41670, In your dreams, maybe. See comments, this forum, from "ran-g", "calabalumba", and "PatriciaJH". Each tense (present perfect and pluperfect) have valid and definite grammatical reasons for being. They are NOT interchangeable.
Learning correct grammar and syntax of a new language is tough enough without fouling the well with information that's out-and-out wrong.