Упражнение 19 и 20 можно даже без перевода.

A
4is being developed
6 are being introduced
B
1A letter is being written at the moment.
2A report was being prepared by John all day yesterday.
3Grammar is being learnt by us now.
4Considerable investments to eliminate air pollution are being made by mankind at present.
5Serious changes in the environment are being brought in the global climate and water balance today.
6Experimental work to solve the problem of environment protection is being constantly carried out by many scientists.
7Plans for the future are being made by the company.
20
формальное подлежащее
1,3,5,6,9
личное местоимение
4,7,10
усилительная конструкция
2,8,11