从句遵循的基本原则是时态一致原则.所谓时态一致,是在把时态确定为三种基本时态的基础上的：过去时,现在时,将来时.比如主句用的某种过去时,从句也要用一种过去时.这是一般情况.
具体到宾语从句中,主句用一般现在时,从句要根据在从句中的具体时态标志来确定时态.
she tells me that she will come tomorrow.
she tells me that she won the first prize yesterday.
主句用一般过去时,从句要用与时态标志相对应的过去时态.比如从句中有过去具体时间或者没有具体时态标志,从句用一般过去时.she told me she won the first prize the day before.从句中有将来时间的标志,用过去将来时（would（will的过去式）+动词原形）.she told me she would won the first prize next day.从句中有完成时态的标志,用过去完成时.she told me she had been in beijing for 3 years.
主句用将来时的很少.从句也用一般将来时.
特别注意,无论主句是什么时态,如果从句句子表示的是一个不变的事实或者客观真理,用一般现在时.the teacher told us the earth goes around the sun.（地球绕太阳转是客观真理）
