Could you please tell me whether the sentence

He has wasted his time when he was at university.

is grammatical? What seems a little bit confusing is that the the present tense (has wasted) refers to the past time (when he was at university).

Actually what I have is a sentence from an English test:

He _____ wasted his time when he was at university.

The answers are: "regrets", "shouldn’t", "ought not to", "shouldn’t have". I suppose that the correct answer is "shouldn’t have". Am I right?

  • 1
    He is at university now: he has wasted his time while he has been at university. He has left university: he wasted his time while he was at university. Jan 20, 2019 at 12:54
  • Could you please take a look at the revised question?
    – Alexey
    Jan 20, 2019 at 13:38
  • @LucianSava I suppose that the correct answer is "shouldn’t have". Therefore the sentence "He has wasted his time when he was at university." ("shouldn't" is removed) must be also correct. Right?
    – Alexey
    Jan 20, 2019 at 13:45

1 Answer 1


Let's look at the answered test question first:

He shouldn't have wasted his time when he was at university.

The verb construction in the matrix clause includes a past-tense modal auxiliary, a bare infinitive, and a participle.  The past-tense form of a modal auxiliary can represent either the past tense or the subjunctive mode.  Here, we take it to indicate tense because it is part of a past perfect construction. 


You want to know how to build a similar sentence without the word "shouldn't".  Let's now look at two options:


He had wasted his time when he was at university.

Here, the first word of the verb construction "had wasted" is "had".  Without the past-tense form "shouldn't", this is the word that must be marked for tense.  For it to be equivalent to the original sentence, it has to be marked for the same tense, the past tense. 

This version preserves the perfect aspect of the original.  We don't have to preserve the aspect.  The perfect aspect forces a past-tense interpretation of "shouldn't".  Without the "shouldn't", we're free to use a simple past-tense construction. 


He wasted his time when he was at university.

Here, there is only one word in the construction "wasted".  That one word is enough to mark the past tense.  We don't have much reason to use the perfect aspect here, and leaving the aspect indefinite is natural.


It's pretty easy to miss that the "shouldn't" in the original is a past-tense form:

I shouldn't waste time in general.
I shouldn't have wasted time yesterday.
I shouldn't waste time now.
I shouldn't waste time tomorrow.

By itself, "shouldn't" doesn't seem to have any tense at all.  It works in past-tense, present-tense and future-tense contexts.  It commonly represents the subjunctive mode of shall not, instead of representing any tense. 

It's also pretty easy to miss that the "have" in the past-tense example doesn't mark tense.  The bare infinitive looks exactly the same as many present-tense forms: to have, I have, we have, you have, they have. 

When we don't use a modal like "shouldn't", tense and aspect are a bit less complicated:

I often waste time.
I wasted time yesterday.
I am wasting time now.
I will waste time tomorrow.

  • Thank you very much for a detailed answer! Is it a typo when you say "it is part of a past perfect construction" instead of "it is part of a present perfect construction"?
    – Alexey
    Jan 20, 2019 at 16:13
  • I maybe wrong but the sentence "He had wasted his time when he was at university." seems to mean that his time was already wasted by the time he was at university. Am I right?
    – Alexey
    Jan 20, 2019 at 16:25
  • No, that's not a typo. The past perfect modal construction is "should (not) have wasted". The matching present perfect construction is "shall (not) have wasted". Of course, that's using the labels past and present for the verb's form, not really for the verb's meaning. This can be confusing because the present-tense forms of "shall" and "will" usually do carry a future-tense meaning. The future tense exists in English semantics, but it doesn't exist in English grammar. There's no such thing as an English future-tense word form. Jan 20, 2019 at 16:26
  • Yes, that's one possible interpretation of "he had wasted". To make that meaning clear we might use "he had already wasted his time . . . ." And, yes, that's a good reason to prefer the simple past-tense construction, if you want the time of wasting and the time of being to be the same past-tense period. Jan 20, 2019 at 16:42

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