1-Yesterday, we had to be careful on that scaffolding because it could collapse.
2-Yesterday, we had to be careful on that scaffolding because it could have collapsed.
3-Yesterday, we had to be careful on that scaffolding because it might collapse.
4-Yesterday, we had to be careful on that scaffolding because it might have collapsed.
Which of the above are grammatical and meaningful?
Obviously, when we were on it, we knew that it was there and had not collapsed.
Gratefully,
Navi
Hi, Navi,
@navi posted:1-Yesterday, we had to be careful on that scaffolding because it could collapse.
2-Yesterday, we had to be careful on that scaffolding because it could have collapsed.
3-Yesterday, we had to be careful on that scaffolding because it might collapse.
4-Yesterday, we had to be careful on that scaffolding because it might have collapsed.
In (1) and (3), could/might collapse points to the future from a past perspective, and is the one that, in my opinion, works finely with had to be careful.
In (2) and (4), I would have said: We should have been careful on that scaffolding because it could/might have collapsed.
