As a native speaker of English, these two sentences sound acceptable to me:

A full refund can be claimed if the school fails to provide a textbook.

A full refund could be claimed if the school failed to provide a textbook.

But is it not the case that there are situations where both present and past tense cannot be used interchangeably when using "if' to create a conditional clause?

  • When I went to school, full marks could be obtained if the pupil answered every exam question correctly. You can't recast that sentence using present tense can, answers. Feb 24, 2015 at 16:08

1 Answer 1


Could is the past tense of can as it is in may/might, will/would. Using a particular form (past or present) must be adhered to.

  • Could I beg to differ? May I beg to differ? Would I beg to differ? Yes I can, yes I might, yes I will. No past tense. Feb 25, 2015 at 12:42

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