So far, not one of them has been struck down by sudden death!

struck是strike的过去式， 他们放在一起是词组， strike down 打倒 击倒的意思。

全句： 到目前为止， 他们当中没有一个被死亡击倒。

到目前为止,他们没有一个人被死亡所吓倒.
struck down 是被击倒的意思,是词组

击倒 是词组

被……打击；被……打倒
struck是strike的过去分词，这里是被动语态。

是的！意思是到目前为止他们没有一个人被突如其来的死亡打倒的。
struck down：
1. He struck down an adversary.
他打倒了一个对手。
2. The explorers struck out at down.
那些探险的人天一亮就出发了。
3. He was struck down by a car.
他被一辆汽车撞倒了。
4. On a dark street I struck him down.
在一条漆黑的街道上，我把他打倒。
5. With one blow he struck down his opponent.
他一拳就把对手打倒了。
6. The rain poured down and struck on the window.
倾盆大雨打在窗户上。
7. A child was struck down by lightning in the storm.
暴风雨中，一个小孩被雷电击倒。
8. A man was struck down by lightning in the storm.
暴风雨中有人被雷电击中了。
9. I had a good right to have struck him down.
我有理由把他击倒。
10. The whole village was struck down by a strange illness.
全村的人都因患一种怪病而倒下了。