Answer:
I hide but my head is outside. What am I?
I'm white and I'm used for cutting and grinding. When I'm damaged people usually remove me. What am I?
I am needed for most animals and hardcover books. What am I?
There are four of us but it seems like everyone loves spades the most.
My voice is tender, my waist is slender and I'm often invited to play. Yet wherever I go, I must take my bow or else I have nothing to say. What am I?
When is it bad luck to see a black cat?