肯定句：主语+used to be
一般疑问句：Did + 主语+ use to be
否定句： 主语+ didn't + use to be
主语+used not to be
肯定句：主语+used to do
一般疑问句：Did + 主语+ use to do
否定句： 主语+ didn't + use to do
主语+ used not to do