Ye Shuhang: In some ways, reference books (参考书) are useful.

these english reference books are. Don't worry!Here are some useful tips to make this school ye There are some books in their bags.------ ------ some books dictionaries are such useful books. Trees are useful to men in three important ways:they give th 英语翻译Trees are useful to man in three very important ways:the Trees are useful to man mainly in three ways,the most import Trees are useful to men in three important ways:They p 1 the 英语翻译Trees are useful to men in three important ways:they giv 英语翻译Trees are useful to man in three important ways:they pro Trees are useful to man in three important ways: They provid 英语翻译Trees are useful to us in three very important ways.They