The sentence in question was on a grammar activity:
During a tour of the factory, health and safety inspectors declared
that the company had to stop / must have stopped production until a
series of tests was carried out.
I naturally chose "had to stop", yet I struggled to explain why. Instinctively, I feel that to use "must have stopped" would require changing the sentence to:
During a tour of the factory, health and safety inspectors declared that the company must have stopped production until a series of tests were carried out.
Are my instincts correct in this? If so, why is "must have stopped" paired with "were" while "had to stop" is paired with "was"?
Best Answer
The correct way to use must is this, which is equivalent to saying had to stop:
Must have stopped would refer to a time further in the past when production actually or was believed to have actually stopped. In the sentence above, the company received a declaration saying they must do X, but we don't know if the company actually did it yet (if penalties are severe that could be strongly implied though)
For example: