台湾籍旅美老师今天交给我们的句子是：

Also in contrast to a camera, your photoreceptors are unevenly distributed, with no receptors for dim light in the very center. This is why faint stars seem to disappear when you look directly at them.
另外一个眼睛和相机不同之处在于你的光感受器并不平均分布；在最中间的地方，没有对昏暗光线的接收器。这就是为什么当我们直视微弱的星光时，星星会消失不见。