What Am I Riddles

Question: I'm measured in temperature and time, but have neither.

What am I?

Question: I'm small but big, i hide behind you but come out when you fall... What am I?

Question: I talk, but I do not speak my mind
I hear words, but I do not listen to thoughts
When I wake, all see me
When I sleep, all hear me
Many heads are on my shoulders
Many hands are at my feet
The strongest steel cannot break my visage
But the softest whisper can destroy me
The quietest whimper can be heard.

Question:

Look at my apple, keep me near.

Listen closely, I'll put worms in your ear.

What am I?

Question: Half of those who read this riddle, I am your best friend.
I depend on you, but it's you I will defend.

What am I?