根据句意和汉语注释，写出单词的正确形式
The man is dead, but his ____________ (精神) lives on.
The doctor advised me to get up and sleep at a ____________ (固定的) time, but I found it very hard.
He is the _____________ (严格的) teacher I have ever met. But I like him a lot.
At that time there was a major land bridge ____________ (连接) Britain to mainland Europe.