英语谜语求答(1) What two words have the most letters (2) Why is a

英语谜语求答
(1) What two words have the most letters
(2) Why is a math book sad
(3) If you look in my face,I am somebody.If you look at my back,I am nobody.
(4) What goes around the world,but stays in one corner?
(5) Forwards I'm heavy.Backwards I'm not.What am
(6) What has four legs,but can't walk?
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