子どものときドーナツを食べました。
- I ate donuts when I was a child.

子どものときドーナツを食べました。 meaning: I ate donuts when I was a child.

The basic sentence structure in Japanese is Subject-Object-Verb (SOV). Let's break down the sentence: ⚫︎ 子ども - Child (Subject, implied in this sentence) ⚫︎ のとき - When (Time marker - at the time of) ⚫︎ ドーナツ - Donuts (Object) ⚫︎ を - Particle marking the direct object ⚫︎ 食べました - Ate (Verb, past tense) The sentence order is: Time + Object + Verb

This sentence showcases two crucial particles: ⚫︎ The particle の (no): indicates possession or a modifying relationship. In this case, 子どものとき can be translated as "the time of a child" or "when I was a child". の connects the noun 子ども (child) to the time marker とき (time/when). ⚫︎ Although not in the example sentence, に is a location particle. Used in conjunction with time words to state "when".

The verb 食べる (to eat) is conjugated into the past tense: ⚫︎ The plain form of the verb is 食べる. ⚫︎ To make it polite past tense, you change the ending る to ました. ⚫︎ Therefore, the past tense polite form of 食べる is 食べました. This conveys the action of eating has been completed in the past.

とき (toki) means "time" or "when". It's a very useful word for expressing when something happened. ⚫︎ It can be used with various nouns to indicate a specific time. ⚫︎ In this sentence, it is used with the noun 子ども (child) to specify "when I was a child". ⚫︎ Other examples include 学生のとき (gakusei no toki - when I was a student) or 夏のとき (natsu no toki - in the summer).

The particle を (o/wo) marks the direct object of a verb. ⚫︎ The direct object is the thing that the action of the verb is performed upon. ⚫︎ In this sentence, the direct object is ドーナツ (donuts) because the action of eating is performed on the donuts. ⚫︎ The を particle always follows the object in Japanese.