Oboeru, Oboeta, Oboeteiru and Oboeteinai

In fact, many people often mistake using these verbs. Please be careful of tense.

Oboemasu/ oboeru: the future tense, the present habitual tense

watashi wa ashita kanji o 10 ko oboeru. (I will memorize 10 kanjis tomorrow.) [future tense]

watashi wa mainichi 10 ko kanji o oboeru. (I memorize 10 kanjis every day.) [present habitual tense]

These sentences mean that I (will) learn kanji and put them into my brain.

Oboemashita/ oboeta: the past tense

watashi wa kanji o 10 ko oboeta. (I memorized 10 kanjis yesterday.) [past tense]

Oboeteimasu/ oboeteiru: the present tense of state

watashi wa kanji o 100 ko oboeteiru. (I know/ have learned 100 kanjis.) [present state]

This describes a state that I have learned kanji and 100 characters are now in my brain. In other words, I haven’t forgotten them.

shogakko no sensei no namae o oboeteiru. (I remember the name of my teacher from elementary school.) [present state]

It means that I have never forgotten the teacher’s name since I was in elementary school. Please makes sure not to say “shogakko no sensei no namae o oboeru”. It means that I will memorize my teacher’s name.

Oboeteimasen/ oboeteinai: negative form of oboeteiru, present tense of state

kino nani o tabeta ka oboeteinai. (I don’t remember what I ate yesterday.) [present state]

It means that I forgot what I ate yesterday.

Moreover, “omoide”（思い出） is memory. Literally the kanji reads that your thought comes out. Its verb is “omoidasu”. When something comes to mind, you would say “Ah, omoidashita” (That reminds me.) When you are trying to recall something, you would say “omoidashiteiru” (present action). Even though you try to recall something to your memory, sometimes you can’t, “omoidesenai” (negative form of potential).

I think it is nice to remember (oboeteiru) many good things, forget bad things quickly and recall (omoidasu) what you have done to reconsider it sometimes.