查看完整版本: there are a number of factors to consider 还是to be considered?

there are a number of factors to consider 还是to be considered?

factors to consider /
   factors  to be considered ?

好像两种用法都有， 为什么？

都可以
具体是省略，前面的句子省略的是there are a number of factors (for people) to consider
后面的是there are a number of factors (that are) to be considered

再给你说两个句子不知道你能不能领会
there is a lot of homework to do
there is a lot of  homework  to be done

i got it
many thks