what's the most important thing is that we must study hard.这句话是不是有问题?

有问题.what's应该是what,what's实际上是what is的简写,所以后面再出现一个is就有两个动词了.这样是对的：what the most important thing is that we must study hard.最重要的是我们必须努力学习.那what's the most important is that we should study hard？一样的，what后面不要加‘s。should和must在语法上的功能是一样的，只是should是应该，must是必须，在程度上有所区别而已。