i will never forget this because of the great effect it had

主句只是I will never forget this,到此为止,后面是because of+名词表明原因.非要说从句的话,就是the great effect it had on my life中的it had on my life,定语从句,用来修饰effect的——但这不是整个句子的从句.
外语类团队《康桥郡》欢迎求助,并欢迎具备一定各种外语知识并热心助人的有志之士加盟,携手并进,共创辉煌!