“诚者不伪，信者不欺”。（）原则是企业经营之本。
A．公正
B．敬业
C．优质服务
D．诚信
参考答案：D
目前国内常用的气体传感器有哪些？
For many years, people （） electric cars. However, making them has been more difficult that predicted.
A. had dreamed of
B. have dreamed of
C. dreamed of
D. dream of
