. Задайте общий вопрос к следующим предложениям: The workers installed the X-rays unit at the plant. Выберите один ответ:
a.
Do the workers installed the X-rays unit at the plant?
b.
Installed the workers the X-rays unit at the plant?
c.
Did the workers installed the X-rays unit at the plant?
d.
Did the workers install the X-rays unit at the plant?
ответ: d.
Did the workers install the X-rays unit at the plant? (d).
Past simple, because the positive sentence is also in the past.