_ What ______ useful book! _ Is it _____ one that you borrowed from Mr Green yesterday?.

I don’t like people ______ talk much but do little.

Some Math problems in this book aredifficult for the studentswork out.

Good news! The price of all those second-hand goods is ________ before.

Only after he had spent several nights working on the math problem_______to wonder whether the problem was wrongly set．