下列说法正确的是（   ）

如图所示为激光液面控制仪原理简图，固定的一束激光AO以入射角θ=60°照射到水平液面，反射光OB射到与其垂直的光屏上，用光电转换器将光信号变成电信号，输入控制系统用以控制液面高度．如果液面降低，发现光点B在光屏上移动了一段距离到B′，请在图中标明B′的位置．（要求画出光路图）

   I  have a good friend．1 name is Peter．We study in Beijing Sunshine Secondary Schoo1．We are in the same(同一个)class．He sits in front of 2 ．His favourite lesson is Music．He  3many CDs．He likes 4 music very much．He likes playing football , t00．After school we  often   play  football in the  5 ．He is very helpful．We often help each 6 ．
   Peter  is  not a Chinese．He is from 7  ．He comes to Beijing 8  his family．His father is  a doctor and his mother is a nurse. They work from Monday    9   Friday．At weekends，his mother  likes shopping and his father likes fishing．Sometimes they go to the park．They all like Chinese  food．They  10   very happy．