up to date,  update,  to date 意思? 用法?

 來源：http://tw.myblog.yahoo.com/tang2002tw/article?mid=7204&prev=7205&next=-1

    1.Up to date（或up-to-date）

          a)形容詞

          b) 新式的/現代的”/到目前為止最新的（=latest）

          例如            

                     I'll keep you up to date with any news．

                    =I'll keep you poster with any news

      2.update

           a)動詞/名詞

           b)更新/使跟上最新近的發展(=to bring…up to date)

           c)例如

              My job is to update database

.           

     3. to date    

          a)直到目前為止(=up to the present momment)

          b)例如

              To date，he has spent a hundred dollars (on/in) the project．

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