单数两个也用单数？如
Readinginbed is bad for eyes .如果是reading和watching做主语呢？也是单数why动名词做主语用单数他不是两个吗要根据所叙述的是一件事还是两件事来确定是单数还是复数WatchingTV and readingbooks are interesting.Goingto bed early and gettingup earlyis a good habit.