The following sentence is a sentence in my composition, and I think it is reasonable to write a sentence in this way. However, a grammar checker has said that the preposition word is unnecessary. Is it a false negative check result?

if children spend much time on watching interesting TV shows


  • You spend money on something, but spend time doing something. Don't ask me why; it's just the way the language works. Jul 12, 2020 at 14:19
  • The inclusion of the preposition after spend ... time is optional before ing-forms like this. 'They spent too much time [on] filling in the form.' I'd say it is more usual to omit the preposition with non-obligatory activities ('They spend too much time watching interesting TV shows'). Jul 12, 2020 at 15:01
  • Both are grammatical, but it's stylistically more common to omit it, just because it removes an unnecessary word. (However, it's not wrong to keep it, especially if there is a specific stylistic reason to do so—perhaps the sentence just before used a different preposition for something else and you want to contrast them.) Jul 12, 2020 at 15:14
  • 1
    "Motorists advised to spend time on research before buying a car", "Why spend time on strategic planning?", "How To Spend More Time On Focused Work" Jul 12, 2020 at 16:00
  • Yes, the "on" is, at best, unnecessary. For once one of those syntax checkers is correct.
    – Hot Licks
    Jul 12, 2020 at 16:39

1 Answer 1


This is yet another case where 'grammar'-checkers unnecessarily confuse inexperienced writers by treating as a hard and fast rule something that is merely stylistic advice. It is true that on is unnecessary, before an -ing form of a verb, when one speaks of spending time. Because it is unnecessary, it simplifies one's writing if it is omitted, and that's why one may be advised to do so. However, one does not violate any rules of grammar if one nevertheless uses it.

The explanation of why such sentences are grammatically correct both with and without on has to do with the well-known fact that, in English, the -ing form of a verb can function as either a gerund or a participle. If, in the OP's example, one thinks of watching as a gerund, then on is required, just as it would be if one had an ordinary noun in that place. On the other hand, if one thinks of it as a participle, then using on would be a mistake. However, although these two ways of looking at watching in this case are very different for the purposes of grammatical analysis, that doesn't make much difference to an ordinary user of the language; for the purposes of advising such a user, one can thus say simply that, in such sentences, on is unnecessary, and that it may therefore be preferable to omit it, but that using it is not incorrect.

In some cases there may, however, be stylistic reasons for using it, which the software cannot take into account. In particular, because on is regularly used in money-related contexts, one may choose to use it for time (and so deliberately ignore the advice), when one wishes to get one's readers to think of budgeting time as analogous to budgeting money (e.g. 'if you spend some time on maintaining the machine now, you will save time in the long run').

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.