A:①②
B:①③
C:①④
D:②③
如图所示,S′为发光点S在平面镜MN中的像,若S发出的一条光线SO经平面镜反射后过P点,请在图中找出发光点S的位置,并完成光路.
Clerk: ____ I help you?
Mary: Yes, please. I want a sweater.
Clerk: What ____ do you want?
Mary: Blue.
Clerk: Here you are.
Mary: How ____ is it?
Clerk: Nine dollars.
Mary: I'll ____ it. Thanks.
Clerk: You're ____.
下列句子中划线成语使用有误的一项是( )