“Do you know that Jack ______ a postman for about six years？” “Yes, I see.”

A．has become

B．has turned

C．has changed

D．has been

根据法律规范的强制性程度不同，法律规范可分为( )。

A．确定性规范和准用性规范

B．委托性规范和准用性规范

C．强制性规范和任意性规范

D．授权性规范和义务性规范