i don't think ( ) possible to master a foreigtn language without much memory work.

问题描述:

i don't think ( ) possible to master a foreigtn language without much memory work.
填it,但是为什么没有is呢 即为什么不是i don't think it is possible to master a foreigtn language without much memory work.

加is的句子就是think后面接宾语从句了(省略了that),也对的
不加is,think后面是接宾语加上宾语补足语,it做形式宾语,后面的不定式才是真正的宾语.