The book is a story book.That book has a red cover.(合并句子0
That book _which___ has a red cover __is_ a story book.
The teacher wrote some words on the blackboard.the pupils copied all of them down.（合并句子）
The pupils copied down__what___The teacher wrote on the blackboard.
Even abottle of water is very important to the man under the bricks.
Even abottle of water_makes___a real difference_to___the man under the bricks.