机头压缩比
参考答案：
机头内分离器支架出口处的截面积与成型段口模、芯模的环形截面积之比。
What does he do?[ ]
A. He is my uncle.
B. He is an engineer.
C. He is funny.
试述原发性高血压病的诊断标准及分级。
