A:−2a>−2b
B:c−a>c−b
C:a+c>b+c
D:a2>b2
已知向量a→,b→满足|a→|=1,a→⊥b→,则a→﹣2b→在向量a→上的投影为( )
- Is Tim Emma's brother? ( )
- Yes, he________.