What Am I Riddles

Question: Though I live beneath a roof,
I never seem to dry.
If you will only hold me,
I swear I will not lie.

What am I?

Question: The more i am present, the less you can see me. Who am i?

Question: You use a knife to slice my head and weep beside me when I am dead.

What am I?

Question: You are my brother, but I am not your brother. Who am I?

Question: I can be dropped from the tallest of buildings and survive,but drop me from the smallest ship and I won't.What am I?