已知两条直线y=ax﹣2和3x﹣(a+2)y+1=0互相平行,则a等于( )
A:1或﹣3
B:﹣1或3
C:1或3
D:﹣1或﹣3
函数y=cos(x+φ+π3)是奇函数,则φ的一个可能取值为( )
—Michael was late for Mr. Smith's chemistry class this morning.
—________? As far as I know, he never came late to class.