Maybe someone did something wrong or damage to the street lights and was required to make up for it. The lights did not been treated as light. I am curious about the story. Nevertherless,you need not pay much attention to this pharase,cause no one use it that way. You can search it online for some mandarin webpage,and there is no such use.

Actually,I think using the word 优美 to describe animals is all right,and sounds creative. But you can make it more naturally by adding ”animal的姿态 or姿势“ , like 狮子的姿态很优美 means the posture of the lion is graceful. or "狮子走路的姿势很优美” means the lion's move is graceful .

I try to explain it more simply for you . when you want to mean MUST ,you can use "须or 必须“ when you want to express NEED, use "需 or必需"

The translation above is perfect. I want to add that this expression and the word"楞" are not commonly used in Mandarin. It is more like a dialect in north area of China. I guess you come across it from some drama lines or novels ?

What I heard about this policy is that if the parents were rural registered permanent residents,and their first child was a girl ,then they have the right to give birth to a second child after 8 years. Therefore,girls usually do not have elder brothers. However,in many area ,especially the less developed area, the family planning policy is not being obeyed.

when you want to say "I know nothing about it",you can use the phrase不了解. when you feel confused or simply do not know ,use不懂. 不懂 connects about the reason in something.