Hi, teachers,Question #: 5: The following sentence is incorrect: If he is a qualified doctor, he should have been able to diagnose the illness.
User's answer: True
Correct answer: False
The above is taken from testing of UsingEnglish.com, but my grammar book tells me the sentence in blue is incorrect.
As a qualified doctor, he should have been able... There is no doubt that he is qualified, and thus the comment about his past ability to diagnose is logical.
If he were a qualified doctor, he should have... This suggests that he is not, and implies that his lack of qualification resulted in a bad diagnosis.
But some native English speakers told me the original sentence make sense to them. I am thoroughly confused and looking forward to your help.