英语：用定语从句合并句子

My uncle had 3 sons,(yet可要可不要) two of whom died during the last earthquake.
My uncle had 3 sons,of whom two died during the last earthquake.
注：
1.虽上下句都以逗号间隔,但of whom引导的均为限制性定语从句,修饰限定先行词sons
2.two与of whom位置关系,可前可后,起进一步补充、限定
3.第一种表述常用,推荐