On FCE we have the following exercise:

  1. Complete the second sentence so that it has a similar meaning to the first sentence, using the word given. Do not change the word given. You must use between two and five words, including the word given.

d. She had to finish her homework before she went out. (until) She had to stay in ________________ her homework.

I'm having a hard time to grasp the two events rule on this one! "She had to stay in until she finished her homework." Sounds perfectly fine to me! Why do I end up with "She had to stay in until she HAD finished her homework."

2 Answers 2


The goal of such exercises is to foster precision in the choice of tenses. There are times, especially in writing, when there is a need for perfect clarity in respect to the sequence of events. Unfortunately, the examples chosen in the exercises often do not establish a context where precision is required in order to avoid ambiguity.

A native speaker might say:

I can't party until I do my homework.

intending that sentence to mean "until I have done my homework", and that's exactly how another native speaker would understand it.

The speaker is explaining why he is unable to party now. He has something important to do first.

I can't party until I have done my homework.
I can't party until I've done my homework.

There, have done expresses completion.

The past tense version of "until I have done my homework" would be

I couldn't party until I had done my homework.
I couldn't party until I'd done my homework.

There, the would-be reveler is explaining why she was unable to party yesterday, perhaps, or last week, or at some other time in the past.

Again, the perfect (here, the past perfect) expresses completion.


Both "until she finished" and "until she had finished" are valid sentences. In context, they mean the same thing.

In general, "had [verb]ed" means that the action was completed at some specified time in the past. "I had seen Bob yesterday." This is usually used with respect to some other action. "I had seen Bob before he saw me."

A plain "[verb]ed" means simply, action completed in the past. "I saw Bob."

The difference is often very subtle. Usually we use "had" when we want to indicate that the action is completed, as opposed to an action that might be ongoing.

  • 1
    I find it interesting to contrast OP's example with They had to work until they dropped. I don't disagree with anything you say above, but I can't see how to use that line of thinking to explain why Past Perfect ...until they had dropped is a complete no-no in my superficially similar alternative. Mar 23, 2017 at 20:33
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    (Personally, I think OP's one is something of a "trick question" - trying to confuse hapless students by including had as part of the Simple Past form of to have to = to be obliged to.) Mar 23, 2017 at 20:37
  • @FumbleFingers Oh, maybe so. Yes, "had" can have the completely different meaning as you say.
    – Jay
    Mar 24, 2017 at 13:12

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