Why is "sự" used before kiên nhẫn but not before kiến thức? Is that because of the words or because of where they are in the sentence?
Kiến thức is already a noun, while kiên nhẫn is an adjective, made into a noun (nominalization) using "sự"
cheers....perfect answer, but how do I say "knowledgeable"
"thông thạo" is the first that comes to my mind.