Please answer the following question: W: Yes. I was awake at that time. It was really loud.  M: I didn't see any lightning though. I thought thunder and lightning always occur together.  W: What makes you believe that?  M: A science book says, when lightning quickly beats the air, it will cause thunder.  W: I guess you didn't read the whole article because the book also says if the lightning is very high in the sky, you might not see that.  What was said before this conversation?
Answer:
M: Did you hear the thunder last night?