Among the visitors-------a group of tourists from abroad.

答案：were解析：这是个倒装句,把Among the visitors提前到句首了,谓语动词的单复数还是根据后面的主语来决定,主语是 a group of tourists,复数形式,所以使用were如有疑问,请追问。无疑后请采纳。书山有路勤为径,学海无涯苦作舟。-----------与君共勉-----------