We all know the air{#blank#}1{#/blank#}us{#blank#}2{#/blank#}．{#blank#}3{#/blank#}makes the air dirty and it makes us unhealthy．Rubbish makes the land and water dirty．The dirty land and water makes us unhealthy and {#blank#}4{#/blank#}too．Trees make the{#blank#}5{#/blank#} {#blank#}6{#/blank#}and beautiful．Trees also give us delicious fruit and useful{#blank#}7{#/blank#}．We should keep the air clean and {#blank#}8{#/blank#}throwing rubbish into rivers, lakes or seas．We should plant {#blank#}9{#/blank#}trees．