宾语从句的时态是这样规定的：主句为过去式，从句需用过去时的某种形式，如一般过去时，过去进行时，过去将来时等（真理、客观事实除外）；主句为现在时，从句可根据需要用所需时态。We all know that he has studied English since 1998. We believed that he had earned enough money to build a house. The teacher told us that the sun rises in the east....
