某工程用双代号网络图进行工程网络计划，在其双代号网络图中有几条虚线，这几条虚线表示工作之间的( )。

A．自由时差

B．逻辑关系

C．先后顺序

D．搭接关系

Swift is a master （）, his satire is usually masked by an outward gravity and an apparent earnestness which renders his satire all the more powerful.