So I built a thick wooden roof over my slit trench, to protect myself from flak.

所以我在我的狭缝沟槽上盖了一个厚木屋顶， 以保护自己免受高射炮弹的伤害。

I told myself that the only way I could be killed in that deep, narrow slit trench was by a direct hit; and I figured out that the chance of a direct hit on me was not one in ten thousand.

我告诉自己，在那条又深又窄的壕沟里，唯一能杀死我的方法就是直接命中；而且我发现，直接命中我的几率不是万分之一。