颗粒的规则度，取决于刀盘的平整度。
参考答案：对
Food safety is important. Rules _____ to stop people from food pollution. [ ]
A. must make
B. must be made
C. can make
D. can't be made
传导速度最快的是（）
A．窦房结
B．心房肌
C．房室交界
D．浦肯野纤维
E．心室肌
