但是突然停电了用英语怎么说

"But suddenly there was a power outage" 可以用英文表示为 "But suddenly the power went out"。

"Power outage" 是由 "power" 和 "outage" 两个单词组成的合成词，"power" 意思是电力，"outage" 意思是停电。因此 "power outage" 的意思就是停电。

例句：

The power outage lasted for several hours. (停电持续了几个小时。)
We were in the middle of dinner when the power outage occurred. (我们正在吃晚饭的时候停电了。)
The power outage caused several trains to be delayed. (停电导致了几列火车延误。)