Are "didn't know" and "hadn't known" grammatically interchangeable? Or is one better than the other?

1 Answer
Apr 26, 2016

Answer:

This is probably a matter of semantics (meaning) rather than grammar (structure). See below.

Explanation:

"hadn't known" is the past perfect tense which implies that the "not knowing" ended before some other event (in the past).

"didn't know" does not necessarily imply such a relationship.

Examples:

I didn't know how to do any of the homework questions.
I hadn't know that I would fall in love before she walked into the room.