我会珍惜 我们所有的回忆
I "ll cherish all the memories about us .（all our memories ）
因为 那些 和你在一起的日子
cause the days with you
是我一生最幸福的时光
is the happinest time in my life.
或者后两句翻得生动一些还可以译成：The hours I spent with you were happiest of my life.(用hour显得再一起的时间更令人珍惜)
整句话就是
I "ll cherish all our memories .Cause the hours I spent with you were happiest of my life.
希望可以帮到楼主~。
