arrive in指到达大地方，如，arrive in China/Japan/Shanghai/Beijing...

arrive at指到达小地方，如，arrive at the bus stop/the library...

get to和reach在表示“到达”意思时没区别。get to 是词组，reach是及物动词，后面接表示地点的名词。如，get to Beijing=reach Beijing. 如果表示地点的词是there或here时，往往用get,不能用get to. 如，Mr Smith got here an hour ago.史密斯先生是一小时前到这儿的。When did you get there? 你什么时候到那儿的？