中国近代史以鸦片战争为开端主要是因为                              ( )        

A．中国第一次被西方国家战败

B．长期闭关锁国状况被打破

C．社会性质开始发生根本变化

D．民族矛盾取代了阶级矛盾

In this factory, suggestions often have to wait for months before they are fully _____.

A．admitted

B．acknowledged

C．absorbed

D．considered