I find it strange that he could/should have passed

[joham]

I find it strange that he could/should have passed the exam without going over his lessons.

Do both modals work for this sentence?

Thank you in advance.

 

[philo2009]

Yes. 'Could' here is equivalent to 'should have been able to...'

 

[Tepal]

Could:

1. To make a polite request
   "Could you open the window, please?"
   "Could you turn up the heat?"
   "Could you remind him to call?"
2. To show possibility ("may" and "might" are stronger)
   "She could be with her parents."
   "It could take you months to find a new place."
   "He could still win, but it's not very likely."
3. As the past form of "can"
   "He said he couldn't come so early."
   "I couldn't remember who he was."
   "They couldn't pass the border."
   

Should:

1. To say what is the right thing to do
   "You should be helping your mother."
   "If he doesn't like the job, he should tell it to his boss."
   "If you knew you were going to be so late, you should have called."
2. To give advice or ask for advice
   "You should try the new restaurant down the street."
   "What should I do? Should I tell him the truth?"
   "Should I try to take the exam again?"
3. To show that something is likely to be true or that it is expected
   "Let's return home, dinner should be ready by now."
   "We should arrive there by twelve o'clock."
   "I should get an e-mail from him soon."

Source: Learn English Modal Verbs

I find that site very informative...it includes pictures too...

I find it strange that he could/should have passed the exam without going over his lessons.

'Could' or 'should' works too. It can be a possibility or 'something is likely to be true or that it is expected'.

Hope this helps.

 

[joham]

Thanks a lot, philo and Tepal. Then, I wonder if we can use both modals in the changed sentence:

I find it strange that he could/should have failed the exam after he studied so hard.

Thank you again.

 

[Raymott]

Thanks a lot, philo and Tepal. Then, I wonder if we can use both modals in the changed sentence:

I find it strange that he could/should have failed the exam after he studied so hard.

Thank you again.

Yes, for the same reason.

 

[philo2009]

'Should' after an expression such as 'it is natural that...' or 'I am pleased that...', often classified as an 'emotive should', is used to indicate the speaker's assessment of, or emotional reaction to, the content of the that-clause. It does not specifically relate to either advice or moral obligation.