如果对He lives in Beijing . 中的画线部分提问,应为:Where does he live ? 这里的where是疑问副词,作状语,替代原句中的地点状语in Beijing。不可说成:Where does he live in ? 因为in是介词,必须带宾语才行,而副词where这里是作状语的,不能作宾语。但如果特殊疑问词是代词,这种结构又必须用in。
What city does he live in ?
Which city does he live in ?
这里的what city和which city都是名词词组,作in的宾语,in不可省,因为live表示“居住”是不及物动词,不能跟宾语,如不能说live a city, live Beijing。
比较
Which room was he born in ? (正) 他出生在哪个房间?
Which room was he born ? (误)