Add punctuation: In addition for a limited time you can buy 2 and get 1 free and you can enjoy Free Shipping to the US and the UK
A: In addition, for a limited time, you can buy 2 and get 1 free and you can enjoy Free Shipping to the US and the UK.

Add punctuation: Internet marketing tools that will surely fire your online business on top
A: Internet marketing tools that will surely fire your online business on top!

Add punctuation: The fighting had French and Belgian troops sent to Rwanda to protect civilians but was open to the regime
A:
The fighting had French and Belgian troops sent to Rwanda to protect civilians, but was open to the regime.