The prescriptive rule is to use "you and I" in the same contexts as "I" (i.e., as a subject 主詞), and "you and me" in the same contexts as "me" (i.e., as an object 受詞、賓語). Well, I presume a lot of people know what "subjects" and "objects" are and I won't go into details here.
最具爭議性係"between you and me" 定"between you and I" 。因為莎士比亞在威尼斯商人一書中曾用過 "between you and I". In "between you and me", since "you and me" is the object of the preposition "between", "me" is the only correct form.
He, him, she, her嘅情況一樣:
例句3: You and he will go to visit the client tomorrow.
例句4: This thing will affect both you and her.
假設 "you" 不存在,例句3變或He will go to visit the client tomorrow,而例句4會係: This thing will affect her.
用這辦法分辨一定冇錯。
喺句子前面用定後面用去决定用"you and me" or "you and I"不一定準確。
Counter example: You can't take on something that you and I couldn't handle.