What Am I Riddles

Question: I'm written with two letters, said with one and seen with two.What am I?

Question: I have a name that's not mine,
and no one cares about me in their prime.
People cry at my sight,
and lie by me all day and night.

What am I?

Question: When you need me, you throw me away. But when you're done with me, you bring me back.

What am I?

Question: It's hard to give up.Remove part of it and you still have a bit.Remove another part, but bit is still there.Remove another and it remains.What is it?

Question: If you have me, you want to share me. If you share me, you haven't got me. What am I?