什么情况下连接词后面直接接被动或ing形式?
例句:quailstypicallyhaveshortroundedwingsthatenablethemtospringintofullflightinstantlywhendisturbedintheirhidingplaces.中的“whendisturbed”为什么不是"whentheyaredisturbed"因为从句的主语和主句主语一致所以省略么?