Answer:
Where can you add 2 to 11 and get 1?
The thinkers usually hold this body part
Once you know it exists, it no longer exists. What is it?
Without this, H2O would just be 2O
A standard dimension for sandwiches and rulers
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?