陶瓷过滤机生产能力影响因素（）
A、给矿量
B、给矿粒度
C、真空度
D、给矿浓度
参考答案：A, B, C, D
They _____ England and they will be back next week. [ ]
A. have gone to
B. have been to
C. have gone in
D. has been on
IGMPv2在IGMPv1的基础上添加了组成员______机制。
