The correct answer is 'you will fail.' Key Points - Unless: We use the conjunction unless to mean 'except if.' - Example: They won't come unless you invite them. - Let us see the meanings of the given words: - Succumb: to stop fighting against something. - Pass: to give something to somebody. - Fail: to decide that somebody is not successful in a test, exam, etc. - Promote: to encourage something; to help something to happen or develop. - Correct Sentence: Unless you work harder you will fail.