题目内容：

根据句意和汉语注释，写出单词的正确形式。

1.Although you failed the exam, you can learn a ________ (宝贵的) lesson from it.

2.The man kept remembering English words every day until he was in his _______ (九十).

3.This is one of the most famous __________(大学) in the USA.

4.He is the ______(严格) teacher I have ever met. But I like him a lot.