Answer:
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.
Different lights do make me strange, thus into different sizes I will change
In we go, out we go. All around and in a row. Always, always steady flow. When we'll stop, you'll never known. In we go, out we go.
Who makes it, has no need of it. Who buys it, has no use for it. Who uses it can neither see nor feel it. What is it?
What do you throw out to use and take in when you're done?
Why was the cook arrested?
Difficult
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?