Whilewe were waiting to land, a flight attendant told us to keep calm and to get offthe plane quietly as soon as it had touched down.
Everybodyon board was worried and we were curious to find out what had happened.
Laterwe learnt that there was a very important person on board.
老师，这里为何不是as soon as it would have touched down 呢？课文用了hadtouched down 是和什么过去后发生的动作比较呢？
另外，能否说成Later we learnt that there had been a very...呢？
1. While we werewaiting to land, a flight attendant told us to keep calm and to get offthe plane quietly as soon as it had touched down.
to keep calm andto get off the plane quietly 指以后发生。在时间状语从句中，依据主将从现原则：应用一般目前时表示一般以后时，用一般过去时表示过去以后时。除此之外，也可以用目前完成年代替以后完成时，表示以后业已完成的动作。也可以用过去完成年代替过去以后完成时，表示过去以后业已完成的动作。也就是说：as soon as it had touched down. 也可以说 as soon as it touched down.
2. Everybody on boardwas worried and we were curious to find out what had happened.
Later we learntthat there was a very important person on board.
不需要 had been 也可。像knew,heard, learnt 等过去时态的“听说，知道”，宾语从句表示状况时，无需用过去完成时。比如，Later I knew he was from the US.
