we are sure that mystery will be fully explained some day by human beings

题目

we are sure that mystery will be fully explained some day by human beings
( )( )( )( )the mystery will be fully explaint some day ……

答案

不能说it is sure that...,要说也只能说It is certain that...,但是都把原句的we的含义给漏掉了.
所以最好改成：
1.We are certain that...
2.We make sure/certain that...