QUESTION: Fix punctuation: Other companies are also experimenting with dual selfie cameras
ANS: Other companies are also experimenting with dual selfie cameras.

QUESTION: Fix punctuation: On the other hand for a maximum df has to be negative and that requires that fxxx0 be negative
ANS: On the other hand for a maximum df has to be negative and that requires that fxx(x0) be negative.

QUESTION: Fix punctuation: The part great room lounge which overlooks the street is a little noisy
ANS: The part "great room" lounge which overlooks the street is a little noisy.

QUESTION: Fix punctuation: pictures photos facts and information on Srar Aqua Park Marmaris
ANS:
pictures, photos, facts and information on Srar Aqua Park (Marmaris)