in (Wo and Wohin): you can be inside or outside ("in die Küche", "in das Zimmer" - and that is why "in den Supermarkt") bei (Wo): for people (bei meiner Mutter, bei dem Chef and that is why "beim Fleischer" but "in der Fleischerei"); for events (beim Karneval, bei einer Feier) auf (Wo and Wohin): for places/spots/squares (auf dem Platz, auf der Eisbahn); for events (auf dem Karneval, auf einer Feier); for institutions (auf der Post, auf der Uni) an (Wo and Wohin): for borders (an der Grenze, an dem Fluss, an der Tür, am Fenster), as well for institutions in a different meaning (am Theater, an der Uni) "am Wochenende" is a time, not a local preposition - different subject Don't confuse it with strict grammar rules. I'm sure, the answer in chinese is correct as too ;-)

Literally translated the words mean the following: bei = near an = at in = inside of auf = on top of although in context, they have different meanings, so for example "auf der Bahn" doesn't mean "on top of the train" but rather "on the train" as in "taking the train" . This is Dativ, since the article for "Bahn" is "die" but with the preposition "auf" it changes to "auf der Bahn", much like in your example "auf dem Markt". The article for "Markt" is "der", in conjuction with the preposition it changes to "auf dem Markt". Prepositions are a fun thing to learn. *^_^*

好的，我知道了；既然没有规律可循，那就背下来好了；谢了, Xinwei!

according to your name, i will answer the question with Chinese:) 德语中介词与名词的搭配是要自己背的，英语也是啊，没什么特定的规律 然后你第二个问题中说的两个都是markt，其实不一样啦，一个是supermakt一个是markt呀，不能因为单词中都有markt就当做要用同样的介词，你还说道这里的两个情况都是静态的，这没错，所以你能看到kaufen IMSupermarkt 和 auf DEM Markt，这两个介词用的都是三格。 希望对你有所帮助！