教室里,初二学生在上物理课。电学部分讲完了。这节课,老师发给每人一个黑盒。“这个盒子黑黑的,很神秘。看,从盒里引出了一红一绿两根导线。”老师说。“这两根导线是连在一起的吗?现在,这是一个谜。”学生一个盒面一个盒面仔细地观看着。“唉,要是有一条缝隙,就可看到盒子里面的东西了!”学 In the classroom, the second grade students take physics lessons. The electricity section was finished. In this lesson, the teacher gave each person a black box. “This box is dark and mysterious. Look, draw a red and green wire from the box,” said the teacher. “Is the two wires connected together? Now, this is a mystery.” The student looks at the box side of the box carefully. “Hey, if there is a gap, you can see something inside the box!”