呼吸困难用英语可以表示为“difficulty breathing”，意思是呼吸有困难。这个词来源于英语单词“difficulty”和“breathing”的结合。“Difficulty”表示困难，“breathing”表示呼吸。

例句：

"I'm having difficulty breathing." (我呼吸困难。)

"She was struggling to breathe." (她呼吸困难。)

"He was wheezing and had difficulty breathing." (他喘气吁吁，呼吸困难。)