about"nicht" In the sentence "Nicht ich habe seinen Apfel gegessen." Is the "nicht" used correctly? Can "nicht" be put directly in front of the "ich"? Or should I say"Ich habe seinen Apfel nicht gegessen."

about "Einkaufen" In this sentence"Möchtest du zum Einkaufen?" What does this "zum Einkaufen"mean? Does "einkaufen" here change to be a noun? Why?

what is the difference between "Alleinstehende"and"Alleinstehender"?

About "the order of the words in German" Is the sentence "Das Kind in das Zimmer ist mein Sohn."correct? Should I change it to"In das Zimmer ist das Kind mein Sohn."? And what's the difference between "Mein Sohn ist das Kind in das Zimmer."and"Mein Sohn ist in das Zimmer das Kind."? Is the second sentence correct? And why?

What is the difference among "für was", " warum", "wofür"

how to use"verheiraten"? Is this sentence"1998 bin ich verheiratet."right? Should I change "bin" to "habe"? What is the difference between "heiraten"and" verheiraten"?

Do"Bachelortitel""Mastertitel"these words really exist?

About "of" why is it "a student of the university", while "a friend of mine"or "a friend of my father's"? why the "university" is not "university's"? And what does "of" mean in the sentence "I don't know of anything that would be suitable."?

Is the sentence "the days when do not show a future." right? Should I change the "when" to "which"?