Iv. поставьте глаголы-сказуемые в соответствующей видовременной форме: 1. quite a large number of definitions (to give) to statistics as a science. 2. the war (to bring) major changes in the programme of statistical work and the methods of observation and processing. 3. all progressive knowledge in the modern world (to tend) to precision. 4. at present many countries (to declare) themselves republics, some of them (to become) independent and encourage the use of local languages. 5. they (to work) there for more than three hours when it (to happen). 6. nowadays some difficult economic problems (to be solved) on the basis of statistical data. 7. a theory (to be known) to be tested by practice.

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.