8.Robots will do most of the housework,________we will have more time for our family  A.so       B.but         C.although          D.if 9.We should have recycling bins in each classroom for _______ things  A.use      B.reuse     C.reused       D.reusable 10.If we plant more trees,the________will be greener A.neighbour      B.soil       C.air      D.neighbourhood 11.All of the machines will have a special card______. A.start       B.to start      C.starting    D.to starting 12.If we _____ all the trees ,there will ne no more oxygen for us to breathe A.cuts        B.cuts off      C.cutting     D.cut down 13.We shuold open all the windows, so we don't_______________use air-conditioners A.havr      B.have to     C.needn't    D.need 14.Plant more trees in the schoolyard because they will provide shade and___the atmosphere fresher A.do    B.make  C.have  D.use