When only after, only if, only in this way etc.Are placed at the beginning of the sentence for rhetorical effect, the subject and auxiliary are inverted:Only after lunch can you play.The question asks for a general answer but gives only one special context.In general, only and but only are not substitutable.*they but only work that way occasionally.Which is grammatically correct?
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I can only do so much in this time.Or i can do only so much in this time.In only when , there is a sense of urgency, a slightly more 'involved' writing.It was only when is by comparision more 'relaxed' writing, more like someone is recounting something to someone.