【问】 a pain in the stomach和a pain in his stomach究竟哪个用法正确呢?

【答】 这两个用法都是正确的。例如：

1. “What was it，Ticki?”“Just a pain in my chest. It’s gone now. ”(Greene)

“怎么啦，提基?”“有点胸痛，现在没事了。”

2. My mother complains of a pain in the/her hip. (CGEL)

我母亲诉说她髋骨疼。

3. The soldier had a terrible wound in his belly. (McArthur)

这个士兵的腹部伤势严重。

4. He received two bullet-wounds in the head. (Chambers)

他的头部受了两处弹伤。

但是，R. Quirk等认为，当提到使人不愉快的身体状况时(如aches，pains，wounds)，人们宁愿使用定冠词the：

have a cold in the head

have spies on the brain

be red in the face

be armed to the teeth