Advanced Details: Why is “I don’t sure” wrong?

"I don't sure" is wrong because "sure" is an adjective, not a verb. The correct way to express this idea is "I'm not sure" or "I don't know". The phrase "I don't" needs to be followed by a verb. "Sure" describes a state of being (certainty), not an action.

Here's a breakdown: 

• "Sure" is an adjective: It describes a state of being certain or confident.
• "Don't" is the contraction of "do not" and is used with verbs: You can say "I don't know" because "know" is a verb.
• "I am not sure" is the correct way to express uncertainty: This uses the verb "to be" in its negative form ("am not") followed by the adjective "sure".
• Correct: "I am not sure if it will rain tomorrow."
• Correct: "I don't know the answer."
• Incorrect: "I don't sure the answer."