简要叙述教师在教学活动中扮演的多种角色。
Your company has an Active Directory domain. You log on to the domain controller. The Active Directory Schema snap-in is not available in the Microsoft Management Console （MMC）. You need to access the Actrve Directory Schema snap-in. What should you do（） ["Register Schmmgml.dll.","Log off and log on again by using an account that is a member of the Schema Administrators group.","Use the Ntdsutil.exe command to connect to the Schema Master operations master and open the schema for writing.","Add the Active Directory Lightweight Directory Services （AD LDS） role to the domain controller by using Server Manager."]
试述水轮机辅助设备渗漏、排水泵检查项目及安全注意事项。
某企业生产甲产品经过两道工序，各工序的工时定额分别为10小时和20小时，则第二道工序的完工率为（）。 ["50%","66.67%","100%","16.67%"]
酶的改性
采用手动准同期并列时，应注意些什么？
