First I admit I myself am not a good questioner, especially in large lectures.
But I do realize the importance of asking questions as a means of learning and doing research, and encourage my students to do so (how?).
Here is a good article that may motivate you in that direction (see the bottom of the exerpt). This is on Leslie Lamport, this year’s Turing Award winner.
(excerpt is from http://research.microsoft.com/en-us/news/features/lamport-031814.aspx)