What are three benefits of implementing vlans？（）
A more efficient use of bandwidth can be achieved allowing many physical groups to use the same network infrastructure
Broadcast storms can be mitigated by decreasing the number of broadcast domains，thus increasing their size
C. A higher level of network security can be reached by separating sensitive data traffic from other network traffic
D. Port-based vlans increase switch-port use efficient，thanks to 802.1Q trunks
E. A more efficient use of bandwidth can be achieved allowing many logical networks to use the same network infrastructure
F. Broadcast storms can be mitigated by increasing the number of broadcast domains，thus reducing theirsize
G. VLANs make it easier for IT staff to configure new logical groups，because the vlans all belong to thesame broadcast domai
双向免疫扩散试验中，沉淀环弯向抗体一方是因为（）。
A. 抗体分子量大
B. 抗原分子量大
C. 抗原浓度高
D. 抗体浓度高
E. 抗体扩散快
竖流式沉淀池其颗粒的沉速为其本身沉速与水流上升速度相等。
A. 正确
B. 错误
控制沉淀池设计的主要因素是对污水经沉淀处理后所应达到的水质要求。
A. 正确
B. 错误
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