Past and Future actions
Incorrect : You should do the work yesterday.
Correct : You should have done the Work yesterday.
Incorrect : It must rain last night.
Correct : It must have rained last night.
Note: When "should" and "must” refer to a future action, they are followed by the simple infinitive but when they refer to the past, they are followed by the perfect infinitive.
To express futurity:
Incorrect : You should have finished it by tomorrow.
Correct : You should finish it by tomorrow.
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