②主句是过去的某种时态，从句一定要用过去的某种时态。 主过从过 At that time,we didn't know why she had missed the flight He told me that he was watching a cartoon film at 10 o'clock this morning②主句是过去的某种时态，从句一定要用过去的某种时态。 • At that time, we didn’t know why she had missed the flight. • He told me that he was watching a cartoon film at 10 o’clock this morning