C )9.He doesn'tknow A.what are the people doing B.how the people are doing C.what the people are doing D.how are the people doing B )10.Do you know_ this problem? A.how about solve B.how to solve C.to how solve D.what to solve 导航页导航页 ( )9.He doesn’t know . A.what are the people doing B.how the people are doing C.what the people are doing D.how are the people doing ( )10.Do you know this problem? A.how about solve B.how to solve C.to how solve D.what to solve C B