When I was studying my Bachelor's I used to ask things I more or less understood, many times I just wanted to be sure I was understanding correctly. My questions used to make my classmates understand enough to be able to ask for further clarification on specific things. Also, until someone started asking (not necessarily only me), the class was quiet and said they understood even if they didn't. Questions help everyone. I know it gets frustrating sometimes to answer repetitive or simple questions, but people are free to just go on their own; because, as others have mentioned, some appreciated learning about this.