[填空题] （）是企业研究与开发能力的基石。

下列各项中，属于加剧产业竞争的主要因素有（）。 ["竞争对手时常更换","产业已进入成熟期","产业进入障碍低而退出障碍高","企业拥有稀缺资源"] You create a Web site that is for members only. The Web site allows members to create lists of users that have access to information about member profiles. The name of the list is stored in the listName variable. The user name of the user to whom access is given is stored in the username variable. You need to enable members to manage their lists of users. Which code segment should you use? （） [" Roles.CreateRole(listName);User.InInRole(listName);"," Roles.CreateRole(listName);Roles.AddUserToRole(useName, listName);"," Roles.RoleExists(listName);Roles.AddUserToRole(useName, listName);"," Roles.RoleExists(listName);User.InInRole(listName)"] 阻塞高压 扩大基层民主，是我国发展社会主义民主政治的重要内容。下列属于基层自治组织的是（）。 ["居民委员会","村党支部委员会","乡镇人民代表大会","业主委员会"] 在信用证业务中，信用证的开立是以买卖合同为基础的，因此，信用证条款与买卖合同条款严格相符是开征行向受益人承担付款责任的前提条件。 （）是企业研究与开发能力的基石。