Breakdown of kyou wa suupaa de yooguruto ga tokubai datta node, takusan kaimashita.
Questions & Answers about kyou wa suupaa de yooguruto ga tokubai datta node, takusan kaimashita.
は marks 今日 as the topic or time frame of the sentence: as for today.
It helps set the scene before the speaker says what happened. In English, we often just say Today, ... at the start of a sentence. Japanese often uses は for that kind of setup.
You could sometimes just say 今日 without は, especially in casual speech, but 今日は sounds more complete and natural here.
で marks the place where something happens.
Here, the supermarket is the place where the yogurt was on special sale and where the buying happened, so で is the natural particle.
に is more often used for:
- destinations
- existence
- points in time
- things you move toward
So スーパーに would not fit this sentence as well.
