没有have a flu ，只有have the flu。flu是influenza的缩写，常与定冠词the连用，但在英式英语中也常省略the。例如：I got flu and was out of commission for a week.我得了流感，一星期没工作。

One of the office girls was down with the flu.

一位女职员得了流感。

Three members of the band went down with flu.

这个乐队有3名成员得了流感。

The school was closed because of the flu.

因为流行性感冒全校停止上课。

I caught a flu and had to lie in the bed.

我得了流感，不得不卧床休息。