“淘宝”“网购”“秒杀”等购物名词，不断更新着我们的视听。这些名词的出现主要说明了[ ]

A．电子计算机的出现

B．汉语词汇不断丰富和更新

C．人们时间观念增强

D．互联网改变人类生活方式

They don't feel safe in our town at night because it _____ so dangerous. There's a robbery every week now.[ ]

A. becomes

B. became

C. has become

D. had become