have flu 为什么不加a

在英语中，疾病名称前是否加冠词取决于该名词的可数性和固定搭配。以下是关于“have flu”不加冠词“a”的具体原因：

1. “Flu”是不可数名词

例：She has measles. (不能说 She has a measles.)

2. 对比可数名词“a cold”

例：I have a cold. (不能说 I have cold.)

例：He has a headache.

3. “Flu”更常用定冠词“the”

例：They stayed home because they had the flu.

通过对比疾病名词的可数性和固定搭配，可以避免类似错误。