John’s success has nothing to do with good luck. It is years of hard work _______has made him a great scientist today.

A．that

B．when

C．which

D．why

( )原则是指建没项目管理的薪酬策略应在社会上进行同类相关比较后保持合理的吸引力。

A．公平性

B．竞争性

C．激励性

D．经济性