在市场上 为什么用on the market啊?看这句：Heis a freelance interpreter working on the private market.-----什么意思?

在市场上 为什么用on the market啊?看这句：Heis a freelance interpreter working on the private market.-----什么意思? 在市场上用英语说是on the market还是in the market在市场上有很多假货 there are many fake commodities on the market 还是in the market!我查字典,on the market 是在市场上待售的意思!字典上有in the market for sth 为什么在地球上是on Earth在月亮上是on the moon 在椅子上是in the chair还是on the chair?为什么?为什么在公交车上是用on而在车里用in? 生活在地球上的英语是live on the earth吗?如果是为什么要用on? Mark the corresponding letter on your answer sheet. it’s got a dirty mark on the cover. 英语句子开头为什么用WHO?例如：who wrote under the pen name Mark Twain on your mark on your mark 为什么在太空用in space,而在地球上用on the earth,都是同类的东西,为什么一个用the,一个不用the,急! K burst into tears_because his teacher punished him in front of the whole class问题里写不下了,选项在这里A.on the side B.on the spotC.on any account D.on the mark mark with 和mark on区别? Mark the place---the map---a cross A.on,with B.on,at 在街道上是 in the street 在忙碌的街道上 on the busy street 在忙碌的街道上 为什么介词不是in是on? 在盘子上 是on the plate 还是in the plate?为什么 So _____that we could hardly see it.A the mark was smallB samll was the markC samll the mark wasD was the mark small为什么? he made a mark on the boat when the sword fell into the 急用!