Fun Riddles

Question: Using 3 periods (.) and 1 question mark (?) make this a logical and grammatically correct sentence:

"That that is is that that is not is not is that it it is"

Question: Travel a mile and I will change.
Travel a million and I will end as I started.

What am I?

Question: You put me on a table and cut me, but you don't eat me.

What am I?

Question: There was once three trees. The first tree did whatever the third tree did, and the third tree did what ever the second one does. What happens if tree number two gets cut down?

Question: While you were folding a letter I got you.
Usually you will do whatever it takes to avoid me,
but now you can't help but find me.

What am I?