cross prism

例句：

1. 1. The crystals in the crystal ball are a perfectexample of how light can be reflected andrefracted through a single medium.
   水晶球中的晶体是光通过单一介质反射和折射的完美例子。
2. 2. The scientist useda special lens to focus sunlight on asmall area of the earth's surface.
   科学家使用一种特殊的透镜将阳光聚焦在地球表面的一个区域。
3. 3. The optician examinedthe eyeglasses with a magnifying glass to make sure they were properlyaligned.
   验光师用放大镜检查眼镜，确保它们正确对齐。