Absolute Knowledge

Question: Something you know nobody knows, and everyone knows something you don't. We all know something, nobody knows everything, and you know something someone doesn't know. What else could nobody know?

Question: During what month do people sleep the least?

Question: People see through me, but none pass through without killing me. I can be anywhere, and can be seen double or single. What am I?

Question: When is 99 more than 100?

Question: What are the next two letters in the following series and why? WATNTLITFS__

Question: Surrounded by life , yet life is its biggest enemy. But without life there is no need for it to exist. What is it?