The following is from Michael Swan's Practical English Usage:

Relative clauses can also be combined with if-clauses in sentences like the following.

I am enclosing an application form, which I should be grateful if you would sign and return.

Then, can relative clauses also be combined with other kinds of adverbial clauses, for example since-clauses in sentences like the following?

It seems something is wrong with this PC, which barely a month has passed since I bought.

  • As for the first example, I wouldn't judge that as a well-formed sentence, from whom?? Commented Oct 29, 2017 at 14:57
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    Is there a reason to think it is not acceptable? Or just the fact Swans doesn't mention them? Sounds totally fine to my ear
    – Unrelated
    Commented Nov 1, 2017 at 22:21
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    @Unrelated you find the OP's last sentence totally fine? It's clearly missing the complement (it).
    – Mari-Lou A
    Commented Nov 2, 2017 at 5:54
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    @Mari-LouA Isn't 'which' the complement? Surely you don't think 'which I should be grateful if you would sign and return it' sounds right
    – Unrelated
    Commented Nov 2, 2017 at 16:21
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    @Mari-LouA Phew. Thank goodness for you! There's a real issue here. :-) [Complements and Adjuncts guys, if you want to write a post!!] Commented Nov 3, 2017 at 0:19

3 Answers 3


Swann missed a big generalization in limiting it to relative clauses and if clauses. Probly it was the "combined with" metaphor that did it. This is not cooking; you don't get a blend, you get a program.

They could have discovered (or rediscovered, depending on the publication date) the Ross Constraints, probably the most important syntactic discovery in the short history of generative grammar.

Details are available in Ross, J. R Constraints on Variables in Syntax, 1967 .

The basic point that's applicable here is that the rule (aka transformation) that forms (relates) relative clauses from (to) their full form, called Relative Formation, is a rule that, as Ross put it, "operates over a variable", meaning that the movement of the relative pronoun to the front of the relative clause can come from indefinitely far down the chained trees of clauses, as long as it doesn't cross certain types of syntactic construction barriers.

E.g, the relative that (which could also be who or whom) is moved from position as object of see

  • the boy that the doctor told his receptionist he never wanted to see ____ again

Question Formation is another rule like that

  • Who did the doctor tell his receptionist he never wanted to see ____ again?

Except that there are exceptions.
These rules can't cross islands, which are kinds of constructions like coordinate structures

  • Frank cooked dinner and Bill washed up ~ *the dinner that Frank cooked and Bill washed up

and complex noun phrases

  • She married the man who wrote that book ~ *the book that she married the man who wrote

These exceptions are the Ross Constraints. They apply to pretty much every English sentence beyond The ball is on the table, which contains no islands.

  • 1
    +1 Nice links/resources. You don't mention specificaly why OP's second example is wonky. I'm assuming it's because the the clause from which the wh-word is extracted is part of an adjunct/adverbial? I looked through the relevant section of Ross, but couldn't find any adjunct constraint or similar. I'm assuming the first example's ok because the if-string is a complement of grateful? Commented Feb 6, 2021 at 23:30
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    Ross doesn't use the term "adjunct"; neither do I. The way it's used these days is not really syntactic. As for the second sentence, I don't really know whether it's covered by one of the constraints or not. All that means is that Ross didn't discover all of them. Commented Feb 6, 2021 at 23:59
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    What I meant by "adjunct" is just "modifier in clause structure'" (I mentioned looking though the Ross just cuz I didn't want you to think I was lazy and asking a question I couldn't be bothered to look up the answer for...) This Q is interesting for me because I was wondering whether, if adverbials/modifiers in clause structure do represent islands, examples like the OP's first one could maybe be used backwards as evidence that various if-strings are or aren't complements. And that would have a bearing on whether there were 1,2 or 3 ifs in English. Most say 2. Pullum says 3. I say 1! Commented Feb 7, 2021 at 2:41
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    I have no idea how many if's there are. Probly plenty; there's at least two any's and three do's, plus several hundred the's. I'll hafta think what a "modifier in clause structure" means. You don't mean the Cycle, do you? Commented Feb 7, 2021 at 4:21

It seems something is wrong with this PC, which barely a month has passed since I bought.

This sentence doesn't work, because it is not obvious what which is referring to (although logically it must refer to the PC). Rather, rewrite it without the phrase about time passing.

  1. It seems something is wrong with this PC, which I bought barely a month ago.
  2. It seems something is wrong with this PC, which I have hardly used since I bought it a month ago.
  3. It seems something is wrong with this PC, which I would like to return, since I only bought it a month ago.


Note that there is a difference between since in your sentence, and since in the respect you would like to use it. If you can replace since with as or because, then it fits the pattern you are asking about. If you cannot, then it relates to a time period, which is something different altogether.

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    My question is "Can relative clauses be combined with adverbial clauses other than if-clauses?". If the sentence doesn't work, what difference from the example sentence in Swan's book with if-clause causes the problem?
    – Aki
    Commented Nov 1, 2017 at 12:33
  • The problem is that your sentence doesn't have a since-clause. It uses the word "since" in terms of a time period, but it is not the beginning of a clause. Therefore, your example doesn't fit the pattern in Swan's book. And, as far as I am aware, so long as you have a proper clause, you should be able to use Swan's idea with clauses starting with if, because, since, although, ... Commented Nov 1, 2017 at 12:40
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    It is used as a conjunction even though the since-clause lacks the object of the verb "bought" (which is "this PC" of course) just like if-clause in Swan's example lacks the object of "sign and return".
    – Aki
    Commented Nov 1, 2017 at 13:16
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    I agree with Aki that since introduces a clause here. Cf. Barely a month has passed since I bought this PC. This works, because since can also introduce subordinate clauses in its temporal sense. In the sentence I have lived here since 2014, it is indeed a preposition (without subordinate clause). I do agree with Peter, though, that there is something different about the since sentence that makes it less felicitous. Is it indeed the word since, or is that a red herring? Commented Nov 4, 2017 at 23:34
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    @PeterAbolins: Mm but I don't think that proves it, the fact that it's broken if you remove since I have bought, because which is part of the clause that you remove: it's a highly complicated construction where two subordinate clauses are not so much nested as intertwined; you can't remove one without harming the other, but the exact rules are not entirely clear here. Commented Nov 6, 2017 at 12:09

I believe the following sentences demonstrate that one can indeed combine relative clauses with adverbial clauses, using other than if-clauses:

  1. Jeff skated slowly, that he should waste time on his journey.
  2. Actions speak loudly, when they speak the truth.
  3. Sally slept soundly, where she had run feverishly all day.
  4. People come here, who love coffee.
  5. Strategies work effectively, which take best advantage of the facts.
  6. Even high level executives can get pushed out, whose motives are found corrupt.
  7. He can advance quickly, whom nature has given good intellect.

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