Hidden work change
Change one word to another to make a new one,one letter at a time.
then put them together ,and create another word when the puzzle finished.
Example:calm-kill:balm;ball;bill;kill
Hidden word:bilk.
问:LEAD-GOLD CAT-DOG
(1)______ (1)______
(2)______ (2)______
(3)______ (3)______
Hidden word:Hidden word