管道中心线用（）表示。
A.粗实线
B.细实线
C.虚线
D.点画线
参考答案：D
______ the new life in Qingdao, the old man lived happily with his son after leaving his home in the countryside.
A．Accustomed to
B．Accustoming to
C．Having accustomed to
D．having used to
