西汉时期非常重视农田水利建设，东汉时命水利专家               负责治理黄河，东汉初期，地方官                 总结劳动人民的生产经验，发明了利用水力鼓风冶铁的___________。

It used to be （） impossible to find vegetarian restaurants outside the major cities, but now they can be found in many towns and cities.

A．fantastically

B．readily

C．virtually

D．primarily