Please correct the usage of comma. Also, if you notice any grammatical errors please correct them too. If there is a better sentence construction please suggest that too.
It feels like I should not be using a comma in any of the following two sentences, but I am not sure.
What is the potent mix in a case study that makes it so powerful that a whopping 73% of people surveyed by CMI use case studies in their marketing?
How can someone maintain your interest in something for a long period of time even when you do not derive any real personal benefit out of it?
Top answer
You are right. Commas are not needed. " Noun clauses never need commas to separate them from another clause.
— Jon Petruch
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The first sentence has a noun clause "that makes it ...." and an adverb clause "that a whopping..."
Noun clauses never need commas to separate them from another clause. Adverb clauses when not at the beginning of the sentence, preceding an independent clause do not need commas either.