英语中在肉店用at the butcher's 为啥不用 in the butcher's

英语中在肉店用at the butcher's 为啥不用 in the butcher's My brother,Tom,in a butcher’s shop（肉店）.He helps the butcher at the butcher's是指在肉店,但如果表示在许多许多肉店要怎么表示呢? at the butcher’s 为何要加撇s were you at the butcher's were you at the butcher's,为什么用were Did you at the butcher's?和Were you at the butcher's? 我指卖肉（butcher）的人在肉店(butcher's)加's变成了他呆的地方 我在tom家 能不能翻译成 I am at Tom's ? 就像at the butcher’s 一样 请教英语的句式He was outside the butcher's.我想问一下为什么butcher后面有 The () is the person who runs the shop ahd the butcher's in Were you at butcher's,too?这里为什么要用"too",而不用"either”