I am new to German and have been using various sites/tools in my quest to become fluent (still a ways off). When working through some word order problems I was asked to translate "In my opinion, Tennis is great." I answered with "In meine Meinung ist Tennis super." I was told the correct answer was "Meiner Meinung nach ist Tennis super." My answer translates correctly using Google and shows the correct grammar using LanguageTool. Which is better and why?
In German you literally don't say »in my opinion«, but »according to my opinion«. And in this construction »according to« has to be translated as »nach«.
»Nach« is a preposition that needs a completion in dative case. This completion is the german word for »opinion«: »Meinung«. But you can't use this word alone. Either you use an article:
Nach der Meinung (according to the opinion)
Nach einer Meinung (according to an opinion)
Or you replace the article with a personal pronoun, but this pronoun has to be used in genitive case (like in english: »who's opinion - my opinion«).
Nach meiner Meinung (according to my opinion)
So the complete sentence could be
Nach meiner Meinung ist Tennis großartig.
(»Großartig« is stylistic a better translation of »great« than »klasse«)
This already is a correct german sentence. But word order is much more flexible in German than in Englisch, so also this version is correct:
Meiner Meinung nach ist Tennis großartig.
And this is also the more common version. The other version (»nach meiner Meinung ...«) is correct too, but less often used, and therefor not the best choice.
The standard word order in German sentences is: subject - predicate - object(s). And this sentences subject is »Tennis«. So in standard word order this sentence would be:
Tennis ist meiner Meinung nach großartig.
But as said before: Word order is very flexible in German. Very often you move that part of speech in the first position that you want to get the highest attention. But there is a rule that you never can break: At position 2 of the sentence has to be the predicate (or a part of the predicate if it has more than one parts, this part has to be the auxiliary verb).
You can not use any translation tool for correct grammar. It extremely depends on style and complexity of sentence structure. So every little child giving you a sentence is better than every tool I am aware of. Start reading and listening German as soon as possible, this is the only way to learn correct grammar. Use translation tools simply for lookup of single words or simple phrases.
First, "my opinion" should be "meiner Meinung." You need the "r," genitive case, because of the possessive, meine.
"Meiner Meinung nach" or "Nach meiner Meinung" are just more idiomatic ways of saying "In Meiner Meinung," which is an Anglicism. In your usage, the clause would occupy the first spot in the sentence, the verb "ist" follows the clause in the second spot, the noun "Tennis" goes into the third (not the fourth), and "super" occupies the remaining position.
You could say (better use klasse for great instead of super):
Nach meiner Meinung ist Tennis klasse.
Meiner Meinung nach ist Tennis klasse. *)
Tennis ist nach meiner Meinung klasse.
Tennis ist meiner Meinung nach klasse. *)
All these are valid. *) sound better. The differences are subtle. Rule of thumb: The first and the last thing in a German sentence have the emphasis.