在市场机制的各要素中，（）是核心。 ["政策","竞争","供求","价格"]
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。
安全目标管理既是一种（），也是调动员工参与生产经营单位管理的有效形式。 ["领导艺术、激励技术","技术措施","管理措施","思想路线"]
网络中的用户共同使用一台网络打印机，这属于利用了网络的（）功能。 ["数据处理","资源共享","数据传输","设备管理"]
简述合同有效成立的条件。
