— ________. He can't save a coin, though.
A:does; No
B:does; Yes
C:doesn't; No
D:doesn't; Yes
设非零向量a→,b→,c→,满足a→=b→=c→,a→+b→=c→,则sin<a→,b→>= ( )
下列对知识归纳,其中错误的一组是( )