I have collected a such sentence:

It's not what you do once in a while, it's what you do day in and day out that makes the difference.

Well,I know what the sentence say,but It have two subject???

  • It's not you, it's me. Syntactically, the two "subjects" there are both it. What is the actual question here? Commented Dec 12, 2016 at 15:49
  • @FumbleFingers I mean,a normal sentence just can have one subject,but it have two.So it is a wrong sentence syntactically?Such as your comment.You just can say It's not you.It's me. (Note that period.)
    – yode
    Commented Dec 12, 2016 at 15:59
  • These examples are compound sentences (with more than one subject or predicate). There's nothing "abnormal" about them - in fact, for all I know compound sentences may be more common than simple ones. It's just that when you're learning English you'll probably be taught the simplest constructions first. Commented Dec 12, 2016 at 16:15
  • @FumbleFingers As your link,you show me three kind of compound sentences.But it is not any one of them in my opinon.For the first kind it have no that Coordinating Conjunctions.For the second kind,it have no that Semicolon.For the third kind,it have no Quotes.
    – yode
    Commented Dec 12, 2016 at 16:22
  • 1
    If your teacher tells you that It's not you, it's me isn't a valid "sentence", I suppose you'll have to accept that if you want to pass whatever exams he's training you for. But for the more general purpose of learning English as spoken / written by competent native speakers, it's a gross oversimplification (and it relies on a very restrictive definition of "sentence"). Commented Dec 12, 2016 at 16:29

1 Answer 1


What's at issue here is not two subjects but two entire independent clauses, each with its own subject and predicate.

It's not what you do once in a while.
It's what you do day in and day out that makes the difference.

When start learning to write your teachers insist on your following certain "rules". One of those "rules" is the prohibition of comma splicing: joining two independent clauses with a comma instead of a conjunction like and or but.

But this isn't a real rule: it's a teaching rule, for children, who tend to run everything together when they write. As you get older, and particularly as you read more and more, you find that rules like this are frequently broken by Real Writers when they have good reasons for doing so.

This is a case where there is a good reason for employing a comma splice. What you have here is two contrasting independent clauses which have the same structure—and which in fact share the same final complement. This is the full thought which underlies the sentence, laid out so you see the parallels:

It's not what you do once in a while [that makes the difference],
it's what you do day in and day out that makes the difference.

The author expresses this as a single sentence to make sure you understand that the first clause is incomplete: it's not a simple declaration, it's an it cleft construction, which isn't finished until it's completed with the relative clause at the end.


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