My first intuition was that the former describes a situation that does not happen yet and uncertainty of whether the speaker leaves by 6 or not and the latter shows some regret like " oh, i thought that i could leave by 6 but i couldn't" However, the answer focuses more on the point of the speaker's leaving. I want to hear native speakers' opinion. What is the meaning difference between two sentences?

2 Answers 2


It's tricky since they're both really saying the same thing, but they'd be used in different contexts with different implications. For the first case, suppose I'm at work and someone asks, "What time will you leave the office today?" I could say, "I expect to leave by 6." This is describing a future event plain and simple.

For the second case, suppose my friend asks what time I'll be at their house later that night. I could response, "I expect to have left by 6, and it takes me an hour to get there, so around 7." This is sort of looking into the future to when I arrive at my friend's, and then looking back to when I actually left.

Saying "I expect to leave by 6, and it takes me an hour to get there, so around 7." means just about exactly the same thing, but it's only looking forward to the event of me leaving. I would say the "have left" formation sounds a little more passive, like the leaving at 6 is planned, but a little more hypothetical. Just saying "leave" puts you more directly responsible for whether you actually leave at 6 or not.

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    I was going to answer but as Matt has done so I'll add mine as a comment. We are saying essentially the same thing. Answer: It is a lot like the difference between, 'here' and 'there'. Both of those words can refer to the same location. Which is chosen depends on the location of the speaker and not on the object being described. The same is true in your sentences with regard to the speakers imagined location in time when speaking. Sep 9, 2015 at 10:26

“To+have+done something" is the infinitive form of the present perfect tense. Here we are using the present perfect to describe something which has been recently completed but still has a bearing on present or future situation.

From (Cambridge Dictionary):

The perfect infinitive can refer to something that will be completed at a point in the future:

For example: "We hope to have finished the building works by the end of March."

The other simpler version “expect + to-infinitive” shows that we believe that something will happen. For example: “We expect to move into our new apartment next week”.

  • Is there a class of verbs that the infinitive perfect form is limited to? I have only seen it used with hope, wish, and expect? Are there others? Sep 9, 2015 at 15:53

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