一.宾语从句中,主句谓语动词如果是现在或将来时,从句可用任何所需时态.
eg.He says he has read the report.
二.主句是一般过去时,从句可使用过去范围的时态（过去进行时、一般过去时、过去完成时）,除客观真理外（要用一般现在时）
1.从句谓语用一般过去式或过去进行时 表示与主句谓语同时发生
eg.I only knew he was studying in a weatern country,but I didn't know what country he was in.
2.从句用过去完成时,表示该动作发生在主句谓语动作之前
eg.He told me that he had told Mary about the meeting already.
3.从句谓语用过去将来时,表示该动作发生在主语谓语动作之后
eg.The reporter asked if the government would take necessery measures to put down the to-do.
