--- He _____be at home,now.  Because I _______ his room just now,and he answered.

-- No,you ________.      

    We are lucky to live in a rich country where we have many things. However, most of us usually1some things.

     Electricity is one thing that we waste most. Lights, TVS, 2and other things are often kept on even when no one is using them. We should turn them off when we do not need them. It takes less than a second to do it. Anyhow, not wasting electricity save money, because we do not have to care forthe electricity we do not use.  The second thing that we often waste is water. Fresh water is precious, 3 it shouldn't be wasted. It is only a simple matter of turning off a tap. I am sure 4  can do this easily if he wants to.  5 big waste is food. My mother 6 cook so much food that much of it was thrown away. I told her we had wasted so much 7. She thought I was right and now cooks mainly  what we can eat.

    It is not 8 to be wasteful. I find there is a simple way of not wasting things. That is to use only what we9. Do not touch what we do not need.  10 this way we can stop being wasteful.

--- It ________be him. He has gone to Beijing.

--- No,you _________.  

--- No, you must not. You _______switch off the electricity first.