A:①②
B:①③
C:②③④
D:①②③④
She talked about the film as if she ____ it.(see)
吸气时,下列有关叙述正确的是( )
已知向量a→=1,1,b→=1,-1,c→=-1,-2,则c→= ( )
先化简,再求值:a(a﹣3b)+(a+b)2﹣a(a﹣b),其中a=1,b=2.