[单选] You are creating a Window Commnunication Foundation (WCF) service application. The application needs to service many clients and requests simultaneously. The application also needs to ensure subsequent individual client requests provide a stateful conversation. You need to configure the service to support these requirements. Which attribute should you add to the class that is implementing the service?（）

已知网络地址为211.134.12.0，要有4个子网，求子网掩码。 关注五指的能力练习，尤其强调加强无名指、小指的训练，体现了五指共用的基本规律。 站在开发管理信息系统的角度看，网络技术、（）和（）．是管理信息系统的三大核心技术。 You have two servers that run Windows Server 2008 named Server1 and Server2. You install WSUS on both servers. You need to configure WSUS on Server1 to receive updates from Server2. What should you do on Server1？ （）  Configure a proxy server。  Configure a upstream server。  Create a new replica group。  Create a new computer grou。 何谓酶生物合成的诱导作用？简述其原理。 You are creating a Window Commnunication Foundation (WCF) service application. The application needs to service many clients and requests simultaneously. The application also needs to ensure subsequent individual client requests provide a stateful conversation. You need to configure the service to support these requirements. Which attribute should you add to the class that is implementing the service?（）