---Can you tell me something about metal ?---Metal making machines and many other things .A.used toB.is used forC.is used asD.is used to
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B解析此题重点考查be used to doing sth、used to do sth 、be used as和be used for doing sth四个个句型结构的区别和意义。be used to doing sth是习惯做某事，used to do sth表示过去常常做某事，现在不做了。be used as是把…用作…be used for doing sth表示被用来做某事。