I've added yet another example for your perusal.
A subject
The word "not" is commonly used to make a sentence negative. For example, "I am happy" becomes "I am not happy" when "not" is added.
stopped
To make this sentence parallel, the verbs and subject must be in agreement. "Clean stalls" would be a phrase that would make this sentence parallel.
The flax was growing beautifully in the garden.
for an example:I added food coloring to the water to make it look pink
value added benefit
Paul added numerous parenthetical statements to his complicated instruction manual to make it easier to understand.
The singer's guttural growls added a powerful intensity to the metal music.
Beveled edges are a common aesthetic nicety added to window panes and mirrors. --Allyy.
Yes, though to make it flow more smoothly, I would write "I have sent an email requesting that you be added to the list."
To exacerbate is to make a situation worse. An example of it used in a sentence is: If you hit her back, it's only going to exacerbate things and start an all out brawl.