1) 如果从句所叙述的为真理或不变的事实,则永远用现在时。
At that time, people did not know that the earth moves.
He told me last week that he is eighteen.
2) 宾语从句中的助动词ought, need, must, dare 时态是不变的。
He thought that I need not tell you the truth.
上一篇: 时态与时间状语
下一篇: 现在进行时代替将来时