这句话借用俗语，表达了命运无常、机遇变化的道理。

水产养殖技术必须兼顾生产力和地球，我们不能为了一个牺牲另一个。

电影的美在于它能够讲述跨越文化和世代的故事。

Read, read, read. Read everything — trash, classics, good and bad, and see how they do it. Just like a carpenter who works as an apprentice and studies the master. Read! You'll absorb it. Then write. If it's good, you'll find out. If it's not, throw it out of the window.

主要的义务规则是那些要求或禁止某些行为的规则。