How often do they have ball games?介绍一下语法特点.

问题描述:

How often do they have ball games?介绍一下语法特点.

How often do they have ball games?的句意为:他们多久进行一次球赛?
这是一个一般疑问句,
how often 是两个词组成的相当于疑问复词的词组,用于问频率(多久一次),
do是疑问助词.