Given this sentence,
Disease occurs only when the virus introduces its nucleic acid into a cell.
Is the following inversion grammatical?
→ Only when the virus introduces its nucleic acid into a cell does disease occur.
Especially the "does disease occur" part.
I think that "occurs disease " is right. Can you explain a rule about this kind of sentence?
Best Answer
Your sentence is right.
A simple way of looking at the rule of inversion is thinking about question and sentence patterns in English.
The question pattern is:
Some learners actually misunderstand the meaning of "v." In the same way that these questions are wrong and unacceptable:
Your alternative is also wrong:
I pointed out these things because the pattern for inversion is the same pattern for questions. And this pattern is:
So,
Only when... does disease occur. = OK