当主句谓语动词为一般现在时的时候,宾语从句可以根据实际情况运用各种时态,当主句谓语动词为一般过去时的时候,从句必须用相应的过去时态（客观真理都用一般现在时）.
例：He says that he lost his book yesterday.
He says that he will go shopping tommorrow.
He said that he would go shopping the next day.
He said that you were a teacher.
He said that the earth travels around the sun.(客观真理)