block of lense

例句：

1. 1. The camera's lens is blocked by a piece of dust.
   相机的镜头被一块灰尘堵住了。
2. 2.The doctor used a lens to examine the patient's eyes.
   医生用一个透镜检查病人的眼睛。
3. 3. The lens of the telescope is very important for observing distant objects.
   望远镜的透镜对于观察远处物体非常重要。