I know I've been asking a lot of questions lately about tenses. But please bear with me here.

NASA scientists have decided to delay the space shuttle's launch in order to determine whether recently repaired parts will cause damage if they break off in orbit.

So for the above example, I know will is correctly used. But I don't understand why there needs to be Present Perfect. Since this happened in the past shouldn't there be Simple Past?

Is this because NASA's decision is continuing into the present?

  • You confuse simple perfect tense and cintinuous perfect tense. Simple Perfect has nothing to do with ongoing action from the past to the time now.
    – rogermue
    Jun 10, 2015 at 20:33

1 Answer 1


The simple past is used to relate or narrate past eventualities. It makes no reference to the present.

The present perfect, however, is not used to relate past events or states: it is a present tense and expresses a present state which in some respect arises out of the past eventuality. That present state is not explicitly named, but is left to the hearer/reader to infer from the discourse context.

One standard use or inference type is the resultative or stative perfect, in which the prior event is inferred to be the cause of a current state. That's what's in play here: the past eventuality, the decision, is understood to explain why the shuttle's departure time is not what was previously expected.

You may read more about this here, or here if you want a much deeper technical analysis.

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