橡胶清管球清除管内（）的效果不够理想.
A.氧化铁粉屑
B.污水
C.磁铁粉末
D.固体杂质
参考答案：C
A terrible example of earthquake which happened in Wenchuan, Sichuan ________ thousands of millions of people die.[ ]
A. led
B. resulted
C. saw
D. produced
吸收、稳定系统在生产过程中的作用？
