忘(わす)れ() wasureがたい gatai事(じ)件(けん) jikenが ga起(お)こ()っ()た() okotta。 An unforgettable incident occurred. notable events~難い (hard to do)
放(ほう)課(か)後(ご) houkagoに ni面(めん)倒(どう)な() mendounaこと kotoが ga起(お)き()た() okita。 Something troublesome happened after school. schoolnotable eventsnominalizer こと