used to do sth中used 是什么词

used to do sth中used 是什么词 used to do sth. used to do sth used to do sth和be used to doing sth中的used是什么词性? used to do sth. 意思 used to do sth,be used to sth ,be used to do sth use的用法.used to do sthbe used to do sth be used to doing sth used to do sth.的中文意思是什么? sb used to do sth.它的否定形式是什么? be used to do sth.否定形式是什么? 区别(used to do sth 和be used to 区分used to do sth./be used to doing/be used to do