Some students hesitate to ask a question. The reason may be varied, it may be that they fear that their companions might mock at them for asking such a silly question, or that the teacher might consider him/her dumb to ask a silly question, or for the simple reason of not disturbing the class.
Whatever might be the reason, remember one thing that you are in the school/college to learn and learning needs a questioning mind. If questions frequently come to the mind of a student, it is a good symbol indicating the active engagement of the students' mind in the learning process.
Questioning makes sure that if you have truly learned or understood the concept well or not. This is a study tips for success which is given by most of the successful tutors from around the world.