The object of 在 is often a place-word and the object of 給 is often the beneficiary of the action expressed by the predicative verb. In Chinese, a prepositional construction comes /before/ the verb it modifies:
他在銀行工作。
She works in a bank.
but not 她工作在銀行。
我給你們介紹一下兒。
Let me introduce you to one another.
but not 我介紹一下兒給你們。
To form a negative sentence, 不 is placed /before/ the prepositional construction:
他不在銀行工作。
我不給你們介紹。
I am not going to introduce you.
Adverbs such as 常, 都, 也 are also placed /before/ the prepositional construction:
我們都在 City Lit 學院學習漢語。
We all study Chinese at the City Lit.
你常給你媽媽信嗎﹖
Do you often write to your mother?
我爸爸也常給我寫信。
My dad also often writes to me.