1.i can't walk any longer,mum.
why?_____,dear?
A.what has happened to you
B.what have you happened
2.the 2008 olympic games______in august in china
A.were held
B.was held
选什么啊，希望能给出详细一点的解释，谢谢！

1.应选A。
happen to(和名词连用)临到...头上(某情况, 尤指不幸的事)，此处是指：妈妈问孩子你到底怎么了，也就是发生什么了，指发生什么意外了。
2.应选A。
the 2008 olympic games 既可以作单数又可以作复数。在语言实际中一般作复数处理。如：The 1992 Summer Olympics were held in Barcelona.由于这是指奥林匹克活动中很多运动项目要举行。而Usually the Olmpic Games is held every four years.就是指奥林匹克这一项活动。