多媒体教室中的投影银幕是用______（粗糙/光滑）的白布做成的．选择这种材料的优点在于：一是利用______（漫反射/镜面反射）使教室内各个座位上的同学都能看到画面；二是白布能反射______光，使同学们能看到色彩正常的画面．
①投影屏幕使用粗糙的白布做成，表面粗糙的白幕布，表面因为粗糙，利用漫反射，能使反射光线射向四面八方，能进入各位同学的眼睛，使同学们都能看到屏幕上的像．
②屏幕是白色的，白色能反射各种的色光，能使同学们看到多彩的画面．
故答案为：粗糙；漫反射；各种色．
| The City Bank was broken into yesterday at 8 p.m.. The police were questioning two men, John Smith and his brother Joseph Smith.
| ||
| 1. The policeman wanted to find the person who . | ||
| A. told a lie B. knew the thief C. went into the bank D. stoic the baseball | ||
| 2. John and Joseph are . | ||
| A. boss and worker B. workmates C. policeman and thiefD. brothers | ||
| 3. The two men told the police the same thing about . | ||
| A. how they got to the restaurant B. the time C. what they ate D. the TV programs | ||
| 4. Neither of the two men . | ||
| A. ate at a restaurant last night B. watched a movie on TV C. knew the name of the restaurant D. liked to eat chips | ||
| 5. Which is NOT TRUE according to their statements? | ||
| A. Joseph got to Join's house at 6 : 45 p. m.. B. There were only a few people in the restaurant. C. They watched TV for about 45 minutes, D. They went back to Joseph's house after leaving the restaurant. |