affect ,是指作用于人的感情：
The adverse criticism the book received didn't affect the author one way or another.
对这本书的敌对性评论丝毫没有影响该作家.
Influence implies a degree of control or sway over the thinking and actions,as well as the emotions,of another:
influence 暗含对他人感情,思想以及行为的控制及左右的程度：
“Humanity is profoundly influenced by what you do” (John Paul II).To
你的所做所为深刻地影响人类 （约翰·保罗二世）.
same是指一模一样的,要与the连用
He loves the red pen.I love the same one.
他喜欢那支红笔.我也喜欢那一支.（指的是同一支笔）
similar是很像的,但不是同一个
He has a red pen.I have a similar one.
他有一支红笔,我有支类似的.（指的是两只不同的比,但是很像）
答案1.influence
2.simila