The right answer is ❓ We say: Can you tell me how to use this machine? After tell me how we normally add to verb. Other examples: She showed me how to cook it. Do you know how to fix it? Using use, using, used here sounds wrong because the sentence needs the base form with to. Description (long details) Many learners get confused with sentences like this. The rule is simple. When we ask someone to explain the way to do something, we use how to verb. So we say, how to use, how to make, how to lea