We had just covered a distance of three miles        the engine         and the car came to a stop

A．then; was broken

B．when; broke down

C．until; was failed

D．since; burst out

随着课程改革的深入，教师要走出封闭、狭隘和垄断的阴影，在新的课程环境下重塑自己并界定角色职能。结合自己的教学实际，谈谈新课程中教师角色将发生哪些转变？