Question

We thought our invention would work
it failed. We will not rest!
we figure out why.
:: until
i: since
= but
than
:: if

Answer 1

We thought our invention would work, but it failed; we will not rest until we figure out why.

Alternatives:
- Since our invention failed, we will not rest until we figure out why.
- If our invention hadn't failed, we might have stopped — but because it did, we won't rest until we know why.