I like playing the  ___小题1:___. I  am Chinese so I  can speak __小题2:___very well and I can speak English too. I  am very __小题3:___and I help my mum to clean our home.I want to be the cleaning ___小题4:___ at school because I want to make our classroom___小题5:____.

已知某工程双代号网络计划的计划工期等于计算工期，且工作M的开始节点和完成节点均为关键节点，则该工作（）。

A．为关键工作

B．总时差等于自由时差

C．自由时差为零

D．总时差大于自由时差