1.This is the best film shown this year.说这话的人估计是看过电影了,于是就不用to be shown 这种带有将要怎么怎么地意思的结构了.这里其实省略了which is,即：This is the best film which is shown this year.
2.Tom was so careless as to leave his car unlocked.
so ...as to do...
too...to do...
so...that...
这几个结构都能表示,太.以至于.
3.前者表示认为做什么事情怎么怎么的.后者表示考虑去做某事.前者这件事做过了,后者还没有