but the big, simple one was 但最重要最简单的一条就是

22. Once upon a time, there was a little tiger
    很久以前 有只小老虎
23. who lived in a cave with her family.
    和家人住在山洞里
24. There were a lot of rules,
    家里有很多规矩
25. but the big, simple one was
    但最重要最简单的一条就是
26. to never leave the cave at night.
    晚上不准离开山洞
27. And the door was so heavy,
    她家的门十分沉重
28. you think it would be easy to remember.
    还以为这样就能让她记住了

来自《疯狂原始人 第二部分 The Croods Part2》第 25 行