QUESTION: Fix punctuation: The main reason is gravity
ANS: The main reason is gravity.

QUESTION: Fix punctuation: The kFreeBSD architectures for the AMD64Intel EM64T and i386 processor architectures are now release architectures
ANS: The kFreeBSD architectures for the AMD64/Intel EM64T and i386 processor architectures are now release architectures.

QUESTION: Fix punctuation: This page shows examples of how to merge and combine data and tables lists using criteria
ANS: This page shows examples of how to merge and combine data and tables (lists) using criteria.

QUESTION: Fix punctuation: When heated to about 900 C breaking the hydrogen bonds between the nitrogenous bases
ANS:
When heated to about 900 C, breaking the hydrogen bonds between the nitrogenous bases.