常用的热电阻有铂电阻和铜电阻，长输管道上主要用铂电阻，常用的结构类型有隔爆型、铠装型、厚膜型等.
参考答案：对
. I first met Mr Zhao nine years ago. He ____ at a chemical college at that time.
A．had worked
B．has worked
C．was working
D．had been working
发动机不易起动，行驶无力，加速发闷，排气管放炮，应检查点火时间是否过迟，分电器触点间隙是否偏大。（）
