Answer:
I am someone you don't know. Who am i?
What you do to determine the length of something
What is seen in the water and in the sky? It is part of the rainbow and can be in your eye
Lots of them make up a word, And lots of words are in them. It's easy when you think about it. A while ago we stamped and mailed them.
if I drink I die if I eat I am fine what am i
People take me on walks and I run and have fun. What am I?