Past Tense - Plain Form

Now that I'm familiar with te-form, verb conjugation to the plain past tense is somewhat simplified. This form is used in the same scenarios as plain present tense - casual conversation, quoting somebody, or acting as a phrase as another part of a sentence (ex. "Fred is good at catching fireflies").

Affirmative past tense essentially means taking the て or で from the te-form and replacing it with た or だ.

Ichidan Verbs

• Remove the る and add た 
• Ex: 食べた、開けた、忘れた、いた

Godan Verbs

• す verbs
•  Replace す with した
• く verbs
• Replace く with いた
• ぐ verbs
• Replace ぐ with いだ
• む、ぶ、ぬ verbs
• Replace む、ぶ、ぬ with んだ
• う、つ、る verbs
• Replace う、つ、る with った
• Ex: 消した、書いた、泳いだ、死んだ、買った

Negative past tense is done differently, however. Rather than conjugating based off the te-form, I instead go from the negative present tense. All plain negative verbs end in ない, so to make them past tense I simply drop the い and replace it with かった.

リーさんは晩ごはんを食べなかった。
Lee-san did not eat dinner.

アリスはコンサートに行かなかった。
Alice did not go to the concert.

ジムは指輪を買わなかった。
Jim did not buy me a ring.

I'll do some sentence practice next so I can incorporate both of these forms. Even if past affirmative isn't as bad as learning te-form from scratch, I still need lots of practice with it.