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

产品创新应坚持（）和差异化的原则，有选择地为不同市场中的客户设计符合其需要的产品。

A、个性化

B、首创性

C、整合性

D、稳定性