与一般胶片不同，X射线胶片双面涂布感光乳剂层，其目的是为了增加感光速度和黑度。
参考答案：对
热辐射的防护措施主要在于
A．多饮水B．加强通风C．降低气温D．隔热E．衣着
As an English major student , I think business English is more practical than other fields.
A．a English student / field
B．a English major student / regions
C．an English major / courses
D．an English student major /sciences
