Напишите формулу образования неправильных глаголов в время

Неправильные глаголы образуют Pаst Simple, не подчиняясь каким-либо правилам, и их приходится запомнить. Обычно эти глаголы даются в конце учебников английского языка за любой класс, или их можно найти в интернете

1. Quite a large number of definitions are given to statistics as a science. 
2. The war brought major changes in the programme of statistical work and the methods of observation and processing. 
3. All progressive knowledge in the modern world is tend to precision. 
4. At present many countries are declaring themselves republics, some of them become independent and encourage the use of local languages. 
5. They had been working there for more than three hours when it happened.
6. Nowadays some difficult economic problems are solved on the basis of statistical data. 
7. A theory is known to be tested by practice. 

1. Quite a large number of definitions have been given to statistics as a science.

2. The war brought major changes in the programme of statistical work and the methods of observation and processing.

3. All progressive knowledge in the modern world tends to precision.

4. At present many countries have declared themselves republics, some of them have become independent and encourage the use of local languages.

5. They had been working there for more than three hours when it happened.

6. Nowadays some difficult economic problems are solved on the basis of statistical data.

7. A theory is known to be tested by practice.