Question

Определить грамматические времена у выделенных предложений и поставить их в вопросительную и отрицательную формы But the most difficult problems the humanity faces are global problems.

Answer 1

Ответ:

But the most difficult problems the humanity faces are global problems. - Present Simple Active

But the most difficult problems the humanity faces aren't global problems.

Are the most difficult problems the humanity faces global problems?

Answer 2

But the most difficult problems the humanity faces are global problems.

Регулярное действие, значит это PS, активный, т.е Present Simple Active.

Вопросительная форма с be в начале:

Are the most difficult problems the humanity faces global problems?

Отрицательная форма с are not:

But the most difficult problems the humanity faces aren't global problems.