If we have when in the sentence, we don’t use Present Perfect:
When plant breeders crossbred wild crops with our domestic crops, they made them just as hardy as their relatives
When did she backslide?
And we are done!
If we have when in the sentence, we don’t use Present Perfect:
When plant breeders crossbred wild crops with our domestic crops, they made them just as hardy as their relatives
When did she backslide?
And we are done!