Sentences that start with an “only” adverbial, usually referring a particular time or condition, have a curious structure as they typically require an auxiliary verb and an inversion. These sentences can come in many tenses, and are usually emphatic. Here’s few examples:
- Only after the sun went down, did the bats come out.
- Only if you finish your homework can you go to the park.
- Only when we had eaten the pie did we realise that it was out of date.
So how do we use this structure?
Only after / when / if inversions
Two clauses connected by an “only after / when / if etc.” adverbial can be reversed like other sentences with multiple clauses and a conjunction – simply requiring the extra inversion of the main verb and subject.
- They cleaned up the river only when it started turning green.
- Only when it started turning green did they clean up the river.
- They cleaned up the river when it turned green.
- When it turned green, they cleaned up the river.
Note that the “only after” adverbial clause does not use a comma, unlike other reversed adverbial clauses.
“Only after / when / if” adverbials can also be used to start sentences that contain only when it is used as an adverb alongside the main verb, too, if you can find the rest of the adverbial later in the sentence (such as after, when, if). The time or condition adverbial needs to be combined with “only” and moved to the front of the sentence. If this is the case, be careful to group all the words together with the adverbial, as the time or condition may be made up of multiple words. How would you reverse these sentences?
- We only found the treasure then.
- You can only read the comic after the football game has finished.
- I only want your help if you’re willing to work quietly.
- He only danced when others weren’t looking.
Remember that the “only after / when etc.” adverbial comes first, then we invert the auxiliary verb (or add an auxiliary verb and invert it), then place the rest of the sentence in the same order as before.
- Only then did we find the treasure. (note that found becomes the bare infinitive find, because have added an auxiliary verb)
- Only after the football game has finished can you read the comic.
- Only if you’re willing to work quietly do I want your help.
- Only when other weren’t looking did he dance.
We add auxiliaries for statements in the simple tenses. We add to do for actions and to be for states. If you have a perfect, continuous or modal tense you won’t have to add an auxiliary verb. When starting a sentence with one of these only adverbials, you always need to put the auxiliary verb before the subject, though.
- They could drive home only after it stopped raining.
- Only after it stopped raining could they drive home.
The purpose of this construction is simple, even if the grammar is a little lofty. We use it to emphasise the condition, or the restriction. This is a strong way to show resistance to doing an action or event, or to emphasise a restriction. The auxiliary verb helps achieve this, in the same way that we might add an auxiliary for other emphatic statements: “I did do my homework – honestly!” “Only after / when etc.” adverbials bring particular attention to the conditions – giving us a negative aspect, rather than a simple sequence of events – to go back to some of our examples:
- Only after the river turned green did they clean it. (implying they waited too long)
- Only if you’re willing to work quietly do I want your help. (implying you have a problem with making too much noise)
Hopefully this helps clear up this construction – if you have any questions, as always, let me know.
What about comma if we use only if in start of sentence
Hi Abdul – I may have slipped up with one or two examples in the post, but generally we won’t use a comma to separate the clauses when the “only if” starts the sentence.
If a sentence starts with only after in present perfect how should we continue,with which tense?(only after the last of the guests has retired to his or her room…………..)
-will the courtyard containing the swimming pool be locked or
-did the kitchen workers feel they could finally relax
Hi Gunce,
This will depend on the context of the sentence; potentially most tenses could be appropriate in the right context, as the “only after…” clause will can be used to indicate different points in time. Generally though, they will correlate as you expect – only after clauses in the past will be followed by past clauses, in the present by present clauses or in the future (or present for future meaning) by future clauses.
E.g.
Only after I complete my homework will I watch TV. (indicating a future time, so followed by a future clause)
Only after I drink coffee do I feel alert enough to work. (indicating present/timeless, followed by a present clause)
Only after they got home did they realise they forget to lock the door. (indicating a past time, followed by a past clause)
Hi Phil,
are these both correct? so that there is a difference in the construction between only after and only when?
only AFTER she had got home did she realise she had forgotten the milk
only WHEN she got home did she realise she had forgotten the milk
Hi Val, yes these are both correct. For the most part they would carry the same meaning, but to be really specific the ‘after’ sentence could refer to a broader timeframe, following returning home, while the ‘when’ sentence suggests it was around the time of homing home that she realised.
Hi, Phil!
I’m very grateful to you for such a useful explanation over this topic.
By the way, is it correct : only after I read your article could I clearly understand this specific use of “only”.
Greetings from Brazil!
Stay well and safe!
Hi Nelson,
Thanks for saying, I’m glad it helps. Yes, your example there is correct!
Only after the Polynesians arrived did those forest disappear.
Those did forest disappear only after the polynesians arrived.
Is it correct??
Hi Parvey,
You’re close, but when we don’t need the emphatic ‘to do’ when the clauses are reversed, and in either case the verb should come after the complete subject ‘those forests’:
‘Those forests disappeared only after the Polynesians arrived.’
Only did he came late he was untidy. Is it correct?
Hi Dan, I’m afraid not; I’m not too sure which meaning you’re going for here but it sounds like you’re looking more the ‘not only…but also’ construction, which I’ve explained here.
The explanation and examples are very helpful.
Thank you, I’m glad it helped!
Hi Phil! What about this inversion: “Only when the pearl was sinking in the sea, did its music become a whisper and the faces of the dead disappeared”? Is the use of the last S. Past correct? I was wondering if it should be a Past Perfect there. Thanks for helping!
Hi Graciela,
It is correct, except that is should be “disappear”, as “did” is our main verb, leaving disappear in the bare infinitive. No, the past perfect is not necessarily as you “Only” sets the time frame – only after the first clause, the second happened. The past perfect would only be needed her is you wanted to create a contrast with another piece of information, for example if you had a sentence before this in a point not as far in the past – but even then I expect this would still be clear.
Best,
Phil
there’s also this one: only by walking can we hope to lose weight (by+ing)
Hi, are there any other tips on how to use only because I am still confused.
Which aspect are you having trouble with? I suppose this article doesn’t start with as simple explanation, but in these cases “only” is used to indicate a condition that must happen for the rest of the sentence to be true. “Only when we finish cooking dinner (condition) will we eat (possible future action)”. It is added to clarify that the condition must be true for the following verb to be true, whereas without “only” such a sentence would just describe a future plan/likelihood.
Phil
Hello. I am still confuse on these sentences. What’s the difference between these:
– Only after I finish all my homeworks do I play video game.
– Only after I finish all my homeworks will I play video game.
– Only after I finish all my homeworks can I play video game.
– Only after finishing all my homeworks can I play video game.
Please elaborate this. I am still confuse on which one to use. Thank you. This helps me a lot.
Could you let me know what aspect of these confuse you? Because the choice depends on your meaning, each verb creates a different idea; “do” would suggest it happens as a regular rule; “will” shows a future intention; “can” describes possibility.
(Also note that “homework” is uncountable and shouldn’t be in the plural.)
Phil
I won’t go to Paris until I improve my French (brush)
– Only after ………………………. I go to Paris.
my attempt : Only after I brush my French up I go to Paris.
Is this correct? This was an exam question.. and that was my answer.. apparently I got it wrong.. but I can find the right answer.
Thank you!
Hi Luna,
You’re close, but missing the future tense: “Only after I brush up my French WILL I go to Paris.” Note, I would also keep the phrasal verb together as it sounds a little simpler.
Phil
Good day sir! How about this sentence, is it correct?
They continued to play until the water turned chilly. Only then Matthew released Miss Murphy from his embrace.
Is the ‘only then’ used here correct? As I received comments saying it was wrong QAQ.
Sorry for the slow response, I’ve been away, but I’d probably amend it slightly, e.g. “Only then did Matthew release Miss Murphy”. We typically use this construction, “Only then did…”; without the “did” it could be confusing as we’d probably take “Only then” on its own to present a contrast, a bit like saying “but then”.
Hello,
Could you explain where to place the sentence stress, intonation?
Hi Diana,
How do you mean? With any sentence in English, really, we can place the stress on different words to give different emphasis…
Phil
Hi Phil,
I was wondering whether this sentence is correct?
“Only if you buy two products you can get one for free.”
It sounds natural to me, but according to the grammar rule of inversion it should be
“”Only if you buy two products can you get one for free.”
Hi Michaela, yes I would say the second version with the inversion is clearer, without the inversion it sounds a little unnatural/unclear.
It perhaps reads a bit far into it but the main confusion here would be if you don’t do the inversion it doesn’t properly connect with only, so grammatically that sounds more like, ‘Only, if you buy two products you can get one for free’ (i.e. like ‘But, if you…’ , as opposed to clearly emphasising ‘It is only if you…’). I hope that makes sense!