急性弥漫性增生性肾小球肾炎时，对毛细血管内皮细胞及系膜细胞增生最直接的影响是（）

A.原尿生成减少

B.肾小球血流量减少

C.肾小球滤过减少

D.毛细血管管腔狭窄

E.尿量减少

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