A:①②③
B:①②④
C:②③④
D:①②③④
每当我想起父亲对我说过的他那______的童年,都使我倍加珍惜今天的美好生活,并催我进取。( )
化简求值:已知α为第三象限角,且cosα-π2=-15,求sin2π-αcosπ+αtanπ-αtanπ+αsinπ-α的值.
函数f(x)=log122x-1的定义域为( )
Liu Wei met his old friends on ______ home yesterday.