My cousin went to Canada two years ago. He ____ there for a few months and then went to America.

A．worked

B．would work

C．would be working

D．has been working

计算机程序设计员要坚持实事求是的工作作风，一切从实际出发，理论联系实际，坚持（）的唯一标准。

A、效率就是生命

B、实践是检验真理

C、客户第一

D、服务第一