QUESTION: Fix punctuation: How can I know whether I eat an authentic and not a fake food
ANS: How can I know whether I eat an "authentic" and not a "fake" food?

QUESTION: Fix punctuation: Can it do the job and will wire and chain hold
ANS: Can it do the job, and will wire and chain hold?

QUESTION: Fix punctuation: On the second floor we offer 5 rooms and a small apartment for our guests On the first floor there is ashared kitchen and living room for the guests
ANS: On the second floor we offer 5 rooms and a small apartment for our guests. On the first floor there is ashared kitchen and living room for the guests.

QUESTION: Fix punctuation: You buy 3 bottles of the testosterone supplement and get 2 bottles free plus a very informative EBook
ANS:
You buy 3 bottles of the testosterone supplement and get 2 bottles free plus a very informative EBook.