用to do 表被动式主动表被动的特殊情况,适用于某些特定的词或句式,主要用于以下几种情况：1.with 结构中,表有事情要做,用 with sth to do ,而不用with sth to be done .2 主系表结构中to do 的宾语是该句的主语：如：The work is easy to do.(不用the work is easy to be done),而如果是形式主语It ,则用该用It is easy for the glass to be broken.3.有事情要做 have sth to do
4.woth sth is woth doing 5.sth require/want /need doing(=to be done)