Explanation
Expresses regret or a missed opportunity: 'if only', 'had I but...'.
Formation
Verb-ば + Verb-past + ものを, い-Adjective + ければ + ものを, な-Adjective/Noun + であれば + ものを, etc.
Detailed explanation
The ～ば～ものを grammar point shows regret about what could have been, often translated as 'if only...' or 'it would have been better if...'. It can be used with verbs, adjectives, or nouns, usually in a past or conditional form.
Examples
Hayaku okireba, chikoku shinakatta mono o.
If only I'd woken up early, I wouldn't have been late.
Motto ganbareba, tesuto ni goukaku shita mono o.
If only I'd tried harder, I would have passed the test.
Okane ga areba, atarashii kuruma o katta mono o.
If only I had the money, I would have bought a new car.
Tomodachi ga ireba, issho ni asonda mono o.
If only I had a friend, I would have hung out together.
Practice
Grammar content sourced from hanabira.org.