He plays football once a week对画线部分提问once a week
问题描述：
He plays football once a week对画线部分提问
once a week
答
How often does he play football?
once a week 是表示他一个星期踢一次足球,既然划线我们就是问他踢足球的频率,而针对这种都是用how often 来提问.
这在新目标英语八年级上册的第一单元学的.