Here are few tests to identify an adverb clause in a sentence. A particular test may not conclusively tell if the clause is adverb, so it’s advisable to apply more than one to be doubly sure.
This post covers how to identify adverb clause. Learn how to identify other dependent clauses as well. (In case you’re used to seeing only three dependent clauses, there are four.)
1. Is the marker word one that introduces an adverb clause?
(A marker word, also called introductory word, introduces or begins a dependent clause.)
Adverb clauses are introduced by marker words such as because, as, since, before, after, until, unless, while, whereas, though, although, even though, if, when, as long as, as soon as, like, where, so that, such that, and many more.
If the marker word of the dependent clause under investigation is from the above list, the dependent clause could be an adverb clause.
This approach has two limitations though.
First, marker words introducing adverb clause are aplenty, implying despite your best effort at memorizing the list, you may come across one that you’re not aware of. These adverb clauses, for example, have been introduced by relatively uncommon marker words.
The proposal was flawless, save that it lacked clear financial details.
In the event that it rains, we will move the picnic indoors.
Supposing that he doesn’t show up, we’ll start without him.
The plan failed insomuch as we underestimated the difficulty.
You can borrow my car on condition (that) you return it by tomorrow. [that is optional]
No explanation was accepted but that he had made a mistake.
By the time the fireman entered the room, it was filled with smoke.
Second, a marker word that introduces adverb clause may introduce noun or relative clause as well. But this limitation is not difficult to overcome as only few marker words overlap. Only when, where, if, and whether introduce adverb clause as well as noun clause. And only when and where introduce adverb clause as well as relative clause. (The two links take you to examples of how each marker word can introduce two different clauses.)
2. Can the clause be moved around in the sentence?
If yes, it’s an adverb clause?
Unlike other dependent clauses, adverb clauses can occupy more than one position in a sentence. So, try moving the clause under investigation from the front to the end (and vice versa), and see if the sentence makes sense. If it does, then it’s an adverb clause. All the sentences below, for example, retain their meaning even if you move the underlined clause to front or back. Hence, the underlined clauses pass the test of being an adverb clause.
Because it was raining, I exercised indoors. [I exercised indoors because it was raining too has the same meaning.]
Let your children suffer a little hunger and a little coldness if you want them to have a peaceful life. [If you want your children to have a peaceful life, let them suffer a little hunger and a little coldness too has the same meaning.]
When I’m not focusing on something, I get lost in thoughts.
The company decided to launch the product, even though it wasn’t completely ready.
This test though wouldn’t work with few marker words such as as if, as though, like, and so that, which can occupy only the end position and hence can’t be moved. In these sentences, for example, you can’t bring the adverb clause to the front position.
The winter chill continued as if it would never end.
You look as though nothing has happened.
He talks like he’s been practicing for years.
Tom works the hardest so that he could rise in the hyper-competitive industry.
Try this test on these two dependent clauses. Can you move them to a different position in the sentence?
What you did was beyond our wildest expectations.
Those who live in a glass house don’t throw stones.
You can’t. The first is noun and the second is relative clause.
3. Does the clause answer adverbial questions?
If the answer is yes, it’s an adverb clause.
If you see the clause answering questions such as when, where, why, in what manner, to what degree, and under what condition, you’ve an adverb clause at hand. (These are common adverbial questions, but they don’t constitute an exhaustive list.) Examples:
Because it was raining, I exercised indoors. [Answers the adverbial question why]
When I’m not focusing on something, I get lost in thoughts. [Answers the adverbial question when]
If you want your children to have a peaceful life, let them suffer a little hunger and a little coldness. [Answers the adverbial question under what condition]
Even though the product wasn’t completely ready, the company decided to launch it. [Answers the adverbial question how two things contrast with each other]
4. Is the marker word subject, object, etc. of the dependent clause?
(This test is for advanced learners as it requires identifying the role of marker word as subject, object, complement, or adverbial in the dependent clause.)
If the answer is yes, it’s not an adverb clause.
A clause – dependent or independent – has its own subject, verb, object, complement, and adverbial (SVOCA). In noun and relative clause, the marker word may or may not be one of SOCA. But in adverb clause, it is never one of SOCA. (It’s SOCA – and not SVOCA – because a marker word can’t be verb.)
An implication of this is that in adverb clause you’ll always find the marker word followed by a noun phrase or pronoun as subject of the clause, which may or may not be the case in noun or relative clause.
I don’t know what he is up to. [Noun clause with he as subject of the clause]
I don’t know what transpired in the meeting. [Noun clause with what as subject of the clause]
I lost the watch that you bought last month. [Relative clause with you as subject of the clause]
I lost the watch that hardly worked. [Relative clause with that as subject of the clause]
I went for shopping when I was free. [Adverb clause with I as subject of the clause. There will never be a case in which when or other marker word will be the subject or object of the clause.]
So, like in second and fourth examples, whenever you see a clause without a noun phrase or pronoun as its subject – and there are plenty of such clauses – you can rule it out as an adverb clause.
5. Rule out other dependent clauses
You can also identify an adverb clause by ruling out the possibility of other three dependent clauses. How do you do that? Refer to the posts on how to identify noun, relative, and comparative clause linked to earlier.
Keep this in mind while applying above tests
Sometimes the marker word may be preceded by an adverb, like in these sentences.
Just where the river bends, the current is stronger. [Just]
Precisely when the alarm goes off, evacuate the building immediately. [Precisely]
Only when he travels for work, he brings back souvenirs for his family. [Only]
My father repaired the overhead tank just as an engineer would. [Just]
In such cases, apply the tests to the entire underlined part.
To end, while applying above tests, remember what was mentioned at the beginning of the post: A particular test may not conclusively tell if the clause is adverb. It’s better to apply more than one to be doubly sure.
