我今天将项目更新到ASP.NETCore2，但出现以下错误:CannotconsumescopedserviceIMongoDbContextfromsingletonIActiveUsersService我有以下注册:services.AddSingleton();services.AddScoped();services.AddSingleton(option=>{varclient=newMongoClient(MongoConnectionString.Settings);returnclient.GetDatabase(MongoConnectionString.Databa