成年人缺乏维生素D将导致（）
A.皮肤病
B.夜盲症
C.脚气病
D.坏血症
E.骨软化病
参考答案：E
采用水力清砂代替风铲清砂是控制振动的( )措施。
A．控制振动源
B．改革工艺．
C．限制振动强度
D．改善作业环境
In relation to employment law, explain the similarities and differences between an employment contract and a contract that a company makes with an outside contractor. (10 marks)
