How can this be 里面都用到了什么语法?

How can this be 里面都用到了什么语法? How can this be true? How can this be?(智力题） 请问He is doutful how the work can be finished this week.是个什么名 This can scarcely be true.翻译下这里为什么会用到can 英语翻译Broken hearts are excruciatingly painful.How can this be 里面蕴含了什么语法知识? how could this be they believe it to be helpful and interesting翻译,用到了哪个语法 急 how can be how can they be how can that be?