题干
Vienna is famous for having many great musicians. ____, Johann Strauss the younger wrote hundreds of wonderful pieces of music there.
A：In fact
B：For example
C：As a result
D：In my opinion
答案(点此获取答案解析）
B
是以MN为轴的对称点，而点 
、A是以PQ为轴的对称点，求证：点 