Answer:
found at the back of the book.
I save lives on the ground and in the air. What am I?
What is seen in the middle of March and April that cannot be seen at the beginning or end of either month?
I can point in every direction but can't reach the destination by myself. What am I?
I have six faces but not even one body connected 21 eyes in total but cannot see.
Whoever made me don't want me. Whoever bought me don't need me. Whoever use me don't know me.