------ ---- useful piece of advice the teacher gave us.为什么用what 请说明理由

useful, useful ( )elephant is ( )useful animal to p( )elephant is ( )useful animal to peopleA an,a B an,the C the,an D /,an回答时请适量说明原因 useful是什么意思 翻译useful useful是什么意思? useful verbs: useful nouns: useful verbs: a useful 8:00p.m.on August 8 用什么介词? useful book前面用什么 a/an/the/ / / an useful animal?还是a useful animal? Useful Sentences和Useful Sentences什么意思? useful idea?还是 a useful idea?哈哈哈 Trees are useful to men in three important ways:They p 1 them with wood andTrees are useful to men in three important ways:They p 1 them with wood and other products,they give them shade,and they help to p 2 drought and floods.Unfortunately（不幸 useful expressions: 是什么意思? useful expressions是什么意思 useful什么意思