proved to be,关于动词ed问题
例句：his answer proved to be right.这里proved 充当动词用吗?为什么不需要be动词?还是别的这种动词+ed 是什么用法,能不能举多几个例子?还有一个问题：I believe that only when they meet adversities or difficult situations can they find out who they are.这句里为什么后面是can they?