pencil beam

例句：

1. 1. The pencil beam was shining throughthe window.
   铅笔光束透过窗户。
2. 2. The teacherused a pencil beam to illustrate the concept.
   老师用铅笔光束来说明这个概念。
3. 3. Theartist focused on the pencil beam and paintedthe scene.
   艺术家专注于铅笔光束，绘制了这幅场景。