两个正弦信号的初相（）称为同相，初相位差为（）称为反相。
参考答案：相同；π或180°
被称为攻邪派的医家是（）
A.张从正
B.刘完素
C.朱丹溪
D.李杲
E.张景岳
Who do you think you'd like __________ with you, a boy or a girl? [ ]
A. to let to go
B. letting to go
C. to let go
D. let go
