Every year about one million tourists visit Stonehenge, which is believed __________before the Pyramids, about 4,000 years ago.

A．to build

B．to have built

C．to be built

D．to have been built

顾实汗一生的政治活动，促进了国家统一，有利于（），为我们统一的多民族国家做出了历史贡献。