Question

Выберите правильную букву
1. Scientist and engineers … developing the ways to reduce the acidity of rains
since the beginning of this century.
A) are C) have been
B) has D) will have
2. The sulfur dioxide … already … greatly to acid formation.
A) contribute C) are contributing
B) has contributed D) contributed
3. They informed that there … suggested a 5% reduction of sulfur dioxide.
A) has been C) had been
B) will have been D) had had
4. The effects of acid rain on aquatic ecosystems … investigated before the end
of the century.
A) has not been C) had not been
B) have not been D) will be
5. We … disconnected already before the talk was over.
A) have been C) will have been
B) has been D) had been

Answer 1

Ответ:

1. C) have been

2. B) has contributed

3. C) had been

4. D) will be

5. D) had been​