-Is your father a Party member ?

- Yes, he    the Party three years ago. He    a Party member for three years  .

A．has joined; has been

B．joined; has been

C．joined ; was

D．was joined; is

（）是各个模块都能引用的部件模型，是计算机并行工程思想在CAD软件中的一种体现。

A、过程模型

B、主模型

C、虚拟模型

D、装配模型