Nearly half a million immigrants，many of them English—speaking， in the country during the last quarter of the nineteenth century．
A. have arrived
B. had arrived
C. arrived
D. have been arriving
网友回答
A. have arrived
B. had arrived
(答案→)C. arrived
D. have been arriving
解析：考查句子结构。这个句子的主语是Nearly half a million immigrants，横线要填的是谓语动词，根据下文的时间可知应该使用过去时。句意：大约有50万移民，其中很多都是会讲英语的在19世纪最后的25年中来到了这个国家。