"My brother sleeps in the crib."

Translation: Mein Bruder schläft in der Krippe.

[Beppe]

I have written "im Krippe" and it was considered wrong. Someone could explain me why?

[Hohenems]

Disclaimer - I'm not a natvie german speaker. "Im" is "in dem" smooshed together. "Dem" is a dative version of maculine and neuter definite articles "der" and "das". Krippe is feminine, so it is "die Krippe". In the dative case, "die" becomes "der". "In der" does not get contracted: http://blogs.transparent.com/german/contraction-of-prepositions-and-definite-articles-in-german/

[Beppe]

thank a lot ... danke schön!