单句改错∶When he came in,the speaker found the listeners seating

单句改错∶When he came in,the speaker found the listeners seating

seating---->had been seated
进来时，演讲者发现听众已经坐好了。

be seated是做好的意思，而“听众坐好”是在过去某时已完成，故用过去完成时。

seating 改为 seated

When he came in,the speaker found the listeners seated!

你好！ find sb doing sth是发现某人正在做某事。 find somebody +done表示发现某人怎么怎么样，处于什么状态或者情况。 此处，是演讲者发现听众都已经就坐了，所以应该用done 修饰，把seating改成seated就可以了。 如有疑问，请追问。