inference/must/should/ have to

English as a Second Language English Vocabulary, Grammar and Idioms
1

Can one say:
[color=red]1-If he has a screwdriver, he should undo the screw in a few minutes.
[color=blue]2-If he has a screwdriver, he must undo the screw in a few minutes.
[color=indigo]3-If he has a screwdriver, he has to undo the screw in a few minutes.

If the meaning is not that “he has the duty to undo the screw in a few minutes”, but that it very likely will take him a few minutes to undo the screw?
He must be able to undo the screw in a few minutes.

Gratefully,
Navi

2
  1. There is no duty on him but this is as long as it is expected to take.
  2. He is expected to take only a few minutes.
  3. He has a duty to do so.
3

Beeesneees,

  1. He can undo the screw with a screwdriver in a few minutes.
  2. He can open the screw with a screwdriver in a few minutes.
    Which one is correct?
  3. He can do the screw with a screwdriver in a few minutes.
  4. He can tighten/fix the screw with a screwdriver in a few minutes.
    Which one is correct?
4

‘Undo’ not ‘open’. You can also use ‘loosen’.

‘Do up’ not ‘do’. ‘Tighten’ would be better though.