it was under the tree that you were taliking to your friend.

it was under the tree that you were talkig to your friend.这是强调句型 强调的是under the tree这个介词短语充当的地点状语 把it was that 这三个词去掉 句子就变成了 you were talking to your friend under the tree 句子结构完整 丝毫未受到影响 这是判断是否是强调句型的依据
it was the tree where you were talking to your friend 语法上是没错的 这句话是where引导的定语从句 先行词是the tree where替代the tree 在定语从句中做地点状语 翻译成这是你跟你朋友聊天时所呆的那棵树 所以从中文意思上看 这句话不是很妥当 不是很符合英语的说话习惯 把where换成under which更好 那句子就是it was the tree under which you were talking to your friend.句子还是定语从句 which替代先行词the tree 做介词under的宾语 整个under which在定语从句中做地点状语 句子直译成 这是那颗你跟你朋友在它底下聊天时的树 或者将句子拆成2个分句来翻译 这是那棵树 你跟你朋友在那棵树底下聊过天 语法上关系副词where可以由介词加which来替换 所以你说where在这句话中等于under which 是对的我的意思是，现在把 under which 用 the tree 分开了，并没有合在一起，这样可不可以不可以哦 如果这句话是it was under the tree which you were talking to your friend. 先行词是the tree 关系代词是which 关系词有2个作用 一是引导定语从句 而是要替代先行词在定语从句中充当成分 关系代词通常在定语从句中做主语 宾语 表语 定语从句是you were talking to your friend 从句不缺主语 不缺宾语 也不存在缺表语的情况 which无法替代the tree在定语从句中做成分的那么关系代词which就无法通过先行词将主从句构成一定的关系 也就不是定语从句了 所以分开 不可以的