—Are you from Germany?
— _________.
A:Yes, I am
B:No, I am
C:Yes, I'm not
D:No, he isn't
如图,△ABC中,∠CAB=120º,AB,AC的垂直平分线分别交BC于点E、F,则∠EAF等于( )
在双链DNA分子中,下列碱基互补配对关系正确的是( )