Перевидите предложения,обращая внимание на время сказуемого
1.Einstein was the physicist who has developed the theory of relativity.
2.I didnt ring him up before I had finished the work. 
3. He will have done his work by the time I am back.
4.Why havent you locked through the mail yet? I have had much work to do today and I am very tired now.
5. We have already applied new methods in our research work.