watashi wa kuji made ni shukudai o owarasemasu.

I will finish my homework by nine o'clock.

Breakdown of watashi wa kuji made ni shukudai o owarasemasu.

• は: topic particle
• 私わたし: I
• を: direct object particle
• に: time particle

Questions & Answers about watashi wa kuji made ni shukudai o owarasemasu.

Why is it までに and not just まで?

• までに marks a deadline: the action is completed any time before or at that point.
• まで marks a span up to the point: the action continues until that time. Examples:
• Bold: 九時までに宿題を終わらせます (finish by 9)
• Bold: 九時まで宿題をします (work on homework until 9; not necessarily finished)
• Bold: 店は九時までです (the store is open until 9)

Could I say 九時に instead? What’s the difference among 九時に, 九時までに, and 九時前に?

• Bold: 九時に = at 9 exactly (scheduled point)
• Bold: 九時までに = by 9 (any time up to and including 9)
• Bold: 九時前に = before 9 (strictly earlier than 9) Choose based on whether you mean an exact time, a deadline, or strictly earlier.

Do I need 私は? When would I use 私が?

• Dropping Bold: 私は is very common when context already makes “I” clear.
• Bold: 私は marks the topic (“as for me…”).
• Bold: 私が marks the grammatical subject and adds emphasis/contrast (“it’s I (not someone else) who…”).
• Bold: 私は九時までに宿題を終わらせます is neutral. Bold: 私が九時までに宿題を終わらせます stresses you specifically will do it.

Why 宿題を and not 宿題が? Can I say 宿題は?

• Bold: 終わらせる is transitive, so the thing you finish takes を: 宿題を終わらせます.
• Bold: 終わる is intransitive: 宿題が終わります (“the homework will be finished”).
• Bold: 宿題を終わります is ungrammatical.
• You can topicalize: Bold: 宿題は九時までに終わらせます (“As for the homework, I’ll finish it by 9”).
• Event-focused alternative: Bold: 宿題が九時までに終わります (“The homework will be done by 9”).