to be done 与 to doing

to doing的结构存在,但是决定其结构的是前面的动词或者介词e.g.:look forward to doing,此结构只做特殊用法,而其意义在于V.+sth,至于to be done 可理解为不定时的被动式,可以从下列句子分清楚:
It is to be built.
It is to building.
二者本身各不相同,其等于情况在张道真的最新语法书中已被删除