① Paper can be r{#blank#}1{#/blank#}. We'd better not throw it away.

② It is important to try to save e{#blank#}2{#/blank#}.

③If we don't protect our e{#blank#}3{#/blank#}, the earth will be destroyed.

④ Our teacher tells us to collect r{#blank#}4{#/blank#} plastic bags.

⑤ Gold, silver and iron are all m{#blank#}5{#/blank#}.

①未能及格{#blank#}1{#/blank#}(v.)

②必要的{#blank#}2{#/blank#}(adj.)

③知识{#blank#}3{#/blank#}(n.)

④考虑{#blank#}4{#/blank#}(v.)

⑤deal{#blank#}5{#/blank#}(n.)

⑥乐器{#blank#}6{#/blank#}(n.)