Example 1: 'Edison invented the light bulb. He had been working on it for years'. Example 2: 'Edison invented the light bulb. It had taken him years'.

In example 1, the past perfect continuous makes perfect sense, as working on an invention takes time and repeated effort. In example 2, the same argument could be made, yet we use the past perfect simple. Why?

Is it the 'dummy subject it'? Is it the verb 'to take years'?

Help please!


3 Answers 3


Is it the 'dummy subject it'?

No, it is a real subject. The It = the invention of the light bulb.

Is it the verb 'to take years'?

No. The verb is to take = to consume time. To use or spend (a specified amount of time) in an action, process, or activity; to require or allocate (a specified amount of time) (to do something). Also with direct and indirect object. Frequently with it as anticipatory subject and clause as complement.


The past perfect tense is used to express the first action of two actions that happened in the past.

In the second example given: 'Edison invented the light bulb. It had taken him years' the first action is that it had taken Edison years and the second action is that he invented the light bulb so the first action is in the past perfect "had taken" and the second action is in the past simple "invented".

Note: the first action doesn't mean it comes first in the sentence, it means it happened first in the past then the second action happened.

An example that will clear the confusion is: "When I arrived home I realized that I have forgotten my suitcase at work."

In this example the order is :

  1. I forgot my suitcase at work
  2. I arrived home
  3. I realized that I had forgotten my suitcase

so I say "had forgotten" in the past perfect, "arrived" and "realized" in the past simple.


You could also in 1. use the simple past perfect: "He had worked on it for years".

And for 2. you could use the continuous: "It had been taking him years".

Whether one uses the continuous or not depends entirely on the nuance one wishes to place on the verb. If one is emphasising the long and arduous process one might employ the continuous. But if one was simply stating the fact of time taken, the continuous would be unnecessary.

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