What makes you apprehensive about public speaking?

Sometimes when I stand in front of a big crowd I get lightly anxious. I begin to forget my words and the points that I’m trying to make. The reason is simply because I have the feeling that someone will laugh at me or make fun of me. I know that every body needs to pay respect to the speaker, but still they’re silence makes it worse. It feels that their silence is my enemy, laughing at me, while I find myself in trouble struggling trying to convey my ideas. Another thing that makes me apprehensive about public speaking is the professor’s presence because it is in her hands to give me a passing grade. Plus she knows what’s right or wrong. Therefore, panicking in failing to deliver my speech properly is an additional issue for me to overcome in this class.