non-past]

Because a past event is also non-controllable, a ために-clause containing a past event also means a reason or cause.

朝 あさ 早 はや く試験

“Because I had an exam early in the morning, I couldn’t sleep well.”

Such uses of ために can be substituted with から or ので (BJ Unit 23). 成績 せいせき

が悪 わる いから、補修授業

“Because my grades are bad, I am taking supplementary classes.” 朝 あさ 早 はや く試験

“Because I had an exam early in the morning, I couldn’t sleep well.”