I have two sentences here :

  1. The problem is hard to solve
  2. The table is too heavy to lift

To the best of my knowledge, the former is an example of tough movement, in which the subject in the main clause is the implied object in the infinitival clause.

The problem is hard to solve the problem

As far as I know, this construction is permitted by the tough adjective (hard). But I yesterday came across the latter sentence (I don't remember where, unfortunately). It sounds fine to me, but I got the urge to rephrase it to The table is too heavy to be lifted because I'm not sure about its grammaticality.I think it's ungrammatical because the adjective heavy is not a tough adjective.

More interestingly, the sentence becomes unnatural (and potentially ungrammatical) when the too is omitted.

The table is heavy to lift

Does anyone have an explanation about this?

  • Both "hard to solve" and "hard to be solved" sound fine to me as well as "heavy to lift" and "hard to be lifted". Commented Apr 30, 2017 at 12:55
  • @SovereignSun I think so, marginally. I should've marked it with "?" instead of "*" Commented Apr 30, 2017 at 12:57
  • Yeh, btw "too" is just an intensifier like "extremely", "very", " so much", and etc. Commented Apr 30, 2017 at 12:59
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    @SovereignSun "The problem is hard to be solved" does not sound grammatical to my AmE ear. There's usually a way to fudge almost anything in English, so there may be a context that could make that grammatical, but it's definitely not ordinary usage. Same for "hard to be lifted".
    – Ben Kovitz
    Commented May 28, 2017 at 21:13
  • 1
    @SovereignSun First, switch to Italian: Lasciate ogni speranza, voi ch'entrate. Then check out my answer here. It won't bring enlightenment, but it may bring equanimity.
    – Ben Kovitz
    Commented May 29, 2017 at 8:56

3 Answers 3


The term you want is tough, not though, because the linguist who first analyzed the construction used tough as the prototypical adjective.

Wikipedia gives a list of 'tough' adjectives which includes hard in the sense "difficult":

[...] amusing, annoying, awkward, bad, beautiful, beneficial, boring, comfortable, confusing, convenient, cumbersome, dangerous, delightful, depressing, desirable, difficult, dull, easy, educational, embarrassing, essential, excellent, exhausting, expensive, fashionable, fine, fun, good, great, hard, horrible, ideal, illegal, important, impossible, impressive, instructive, interesting, irritating, loathsome, necessary, nice, odd, painful, pleasant, pleasurable, rare, risky, safe, simple, strange, tedious, terrible, tiresome, tough, tricky, unpleasant, useful, and weird. This construction is also possible with noun phrases like a pleasure, a breeze, or a cinch.

It is also pointed out at that link that

The tough movement construction is similar to but distinct from pretty constructions and adjectives modified by too or enough:

These pictures are pretty to look at.
Lee's mattress is too lumpy to sleep on.

For one, these latter constructions do not allow an alternate form with an unraised object:

*It is pretty to look at these pictures.
*It is too lumpy to sleep on Lee's mattress.

or fronted infinitive:

*To look at these pictures is pretty.
*To sleep on Lee's mattress is too lumpy.

Constructions with too are 'comparatives', where the infinitival is the complement of the 'comparator' too.

  • 1
    @user178049 It isn't ordinarily treated with explicit comparatives, but a) It follows the same pattern of 'indirect' complementation: that is, too .. to parallels as .. as and more .. than. b) There is an implicit comparison: A is too X to VERB implies that the X of A is greater than the greatest X which permits VERB. Commented Apr 30, 2017 at 14:13
  • The comparator too?? Too is an adverb. She is just too rich. [overly rich]. That an adverb. In fact, with or without too, the structure is the same: This math is hard to understand. This math is too hard to understand. It's not a comparative at all.
    – Lambie
    Commented Apr 30, 2017 at 14:46
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    @Lambie OP's question goes to adjectives which do not license infinitival complements--big, for instance. You can't say This bank is big too fail, but you can say This bank is too big to fail. It is too which licenses the infinitival here. Commented Apr 30, 2017 at 14:56
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    Here's my issue with some of your answers. I have to wade through them and try to understand some of the terms you use. "To license infinitival complements"? To license, really?? There is no "greater than" meaning here at all. The basic structure is: X is [adjective] TO [action verb].
    – Lambie
    Commented Apr 30, 2017 at 15:58
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    @Lambie Then how do you explain the fact that you can say "The bank is too big to fail" but you cannot say "The bank is big to fail"? ... As to the diction, I try to suit it to the questioner; this user is sophisticated enough to be familiar with "tough movement", which is pretty recondite. Commented Apr 30, 2017 at 16:12

[1] The problem is hard [to solve ___].

[2] The table is too heavy [to lift ___].

The bracketed expressions are both 'hollow' clauses where the objects of "solve" and "lift" are missing but retrievable from antecedent expressions; here the NPs "the problem", and "the table" respectively.

Functionwise, the hollow clause in [1] is embedded within a predicative complement, licensed by "hard" (items like "good", "bad", and "nice" also allow this).

In [2] the hollow clause is an indirect complement licensed by "too".


Basic structures:

For me these two examples are examples of the word TO used as an operator. Not an infinitive. The TO functions to reveal a purpose, result, outcome or opinion. A) This book is easy to read. This question is hard to understand.

B) My advice is to work more. His idea is to sing loudly.

For me, these other two examples are infinitive complements, grammar-wise.

In sentences patterned like as the ones in A) above, you can add, basically, any adjective and precede the adjective with an entire range of adverbs.

This book is extremely complex to understand. This question is very easy to solve.

When you have: subject + predicate + TO as an operator + a result or purpose in the form of a verb, any adverb can be placed in front of the adjective.

The adverb TOO is very common in English.

The sentence: /The table is too heavy to be lifted/ is not really grammatical. You could say: The table is too heavy to be lifted by us. However, it is not very idiomatic. Idiomatic is: The table is too heavy FOR US to lift.

What is grammatical is: /The table is too heavy (for us) to lift/

For the passive tense, you'd have to have something like this:

The lecture is too hard to be understood [by many students].

The speech is too long to be noted down by hand.

What determines A) is this: Can you take: The book is easy to read and make it: To read a book? The question is hard to understand: to understand a question.

So, the VERB after the TO OPERATOR has to make sense in this kind of transformation:

The bank is big to fail. To fail a bank: doubtful.

One does not "fail" a bank, though, conceivably, a regulator might fail a bank in an audit. To fail the bank [in the audit]. What has to examined is: whether the VERB can be made into a regular infinitival phrase with the noun. That's the question. The question is not about the adverb.

Compare the example above to:

Kids are hard to fail [to not support someone]. To fail kids. Yes, you can fail kids. Not be around to support them, for example. And also, the other meaning as to cause not to pass a test or exam: to fail kids.

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