如果一个人患有严重的流感，可以用英文表达为 "to have a severe case of the flu". 流感，又称感冒，是一种常见的传染病，通常由流感病毒引起。它可以通过飞沫传播，比如打喷嚏或咳嗽时细菌和病毒会从口腔或鼻子飞溅出来。
例句：
She was hospitapzed because she had a severe case of the flu. 她因为患了严重的流感而住院。
He caught a severe case of the flu from his coworker. 他从同事那里染上了严重的流感。
The flu season is here, so make sure to get your flu shot to avoid getting a severe case of the flu. 流感季节到了，所以一定要接种流感疫苗，以避免患上严重的流感。