I plan to go back home to visit my family during the Spring Festival, but if I can't get the train ticket, I still

have an________plan: to visit the museums.[ ]

A．alternate  

B．alternative

C．absolute  

D．appreciable

项目合同争议和纠纷产生的原因有( )。

A．主观意愿分歧

B．不可预见的原因

C．合同条款理解不一致

D．在执行过程中发生的人为原因

E．合同本身存在缺陷的原因