Answer:
I'm written with two letters, said with one and seen with two. What am I?
I am the building with the most number of stories. What am I?
What force and strength cannot get through I with my unique teeth can do.
I am the state when a person is holding a person inside
I transfer oxygen from the atmosphere to your blood
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.