I've always wondered about this kind of sentence:

You can't do (it); you have to wait for it to be (done).

Is the "done" necessary? Without done, is it allowed so in any other type of writing, or is the "done" understood? To me, it sounds incorrect because of the change in tense (as it would become "You can't... for it to be do") but could be allowed in specific types of writing, like poetry, where sometimes, words and phrases are shortened and sometimes omitted to make the lines rhyme. Also, does the requirement change when "it" (in "You can't do (it)") is not there either, or when the ";" before the second "you" is replaced with ","?

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    I can help with one of your questions: there are no rules in poetry, so anything is allowed. "Not you do it can" could be a line of poetry. It might not be good poetry, but that's a subjective question.
    – gotube
    Mar 3 at 1:49
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    The "done" part isn't usually omitted from such sentences. The "it" in "You can't do it" is only left out in an incredulous exclamation: "Before my high-wire act I drink a bottle of whisky." "You can't do!" BTW, instead of saying something else is "not there too", we say it's "not there either". Mar 3 at 3:06
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    @OldBrixtonian That's interesting; I speak AmE and have never heard something like "you can't do" (with nothing following). We might instead use the expression "You don't say!" Mar 3 at 6:03
  • @MarcInManhattan: Very interesting. Likewise "You can't have done"? Maybe we get more astonished than you! The same with "He shouldn't do" and other modals? "You don't say!" never completely lost its US accent here, where I think it was only used ironically - for something completely un-surprising. I haven't heard it for a while. Displaced by dur perhaps. Mar 3 at 12:05
  • @OldBrixtonian Nope, we don't say "you can't have done" or "he shouldn't do" either. Those expressions would sound incomplete here. Mar 3 at 16:08

1 Answer 1


If there was a contest to create a short sentence that illustrates English's idiosyncrasies, this would be a serious contender. :)

So there's a lot going on here.

A) Infinitives and verbs used with modals don't use the concept of tense. They are not "past, present, or future" (and English doesn't really have a "future tense* because future is expressed with a modal).

Infinitives usually (not always) are in the form to X where X will be the same form of the verb you use in commands/imperatives.

Modals will look like can X, could X, may X, might X, will X, would X, should X, shall X, must X, ought to X where X will be the same form of the verb you use in commands/imperatives.

Both of the above, adverbs or can come between the the word and X.

B) Be X, where X is the past-participle form of a verb, is used to express passive voice. The tense of a verb in passive voice is controlled by be, not by X. Infinitive passive voice is possible and that's to be X, which has no tense because it's infinitive.

C) Have to X is equivalent to must X - X in this case is an infinitive and again, no tense. (Getting really fun: have to X can be infinitive and passive too: e.g. to have to X, and to have to be X)

The only verb in that entire sentence that has a tense is have. Everything else is attached to infinitives or modals.

Now let's talk about omitting the words.

You can't do; you have to wait for it to be.

Again, to be X doesn't have a tense, nothing you do can affect what's not there.

The poetic effect of omitting the words here is to put emphasis on do and be as opposites - you cannot take action to get a result you want, you must wait for the result to exist.

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