My arrival was timed perfectly; it was the second weekend of November, when the world largest wine auction ________.

A．held

B．was being held

C．was held

D．was to hold

______是产业间适应激烈竞争的一种自救方式，对于重新搭建和稳定产业链、保证上下游产业间合理利益，维护产业安全具有重要作用。

A．知识产权

B．技术壁垒

C．贸易壁垒

D．战略协作