Do you know __________? A.what happened to him? B.what the matter is with him?请用排除法!
大家都觉得B是错的，
他怎么了？What's the matter with him?-----这个应该是疑问句语序吧？
当怎个疑问句作为宾语从句时应按照陈述句语序，对吧？
所以应该是Do you know what the matter is with him?
哪有问题？