在ARM模板中，参数部分的"reference: {}"属性用于指定参数的值将从另一个资源中获取。这通常用于将一个资源的属性作为输入传递给另一个资源。

下面是一个示例，展示了如何在ARM模板中使用"reference: {}"属性：

"parameters": {
  "resourceGroupName": {
    "type": "string",
    "defaultValue": "myResourceGroup",
    "metadata": {
      "description": "The name of the resource group."
    }
  },
  "virtualNetworkName": {
    "type": "string",
    "defaultValue": "myVirtualNetwork",
    "metadata": {
      "description": "The name of the virtual network."
    }
  },
  "subnetName": {
    "type": "string",
    "defaultValue": "mySubnet",
    "metadata": {
      "description": "The name of the subnet."
    }
  },
  "virtualMachineName": {
    "type": "string",
    "defaultValue": "myVirtualMachine",
    "metadata": {
      "description": "The name of the virtual machine."
    }
  }
},
"resources": [
  {
    "type": "Microsoft.Network/virtualNetworks",
    "apiVersion": "2020-06-01",
    "name": "[parameters('virtualNetworkName')]",
    "location": "[resourceGroup().location]",
    "properties": {
      "addressSpace": {
        "addressPrefixes": [
          "10.0.0.0/16"
        ]
      }
    }
  },
  {
    "type": "Microsoft.Network/virtualNetworks/subnets",
    "apiVersion": "2020-06-01",
    "name": "[concat(parameters('virtualNetworkName'), '/', parameters('subnetName'))]",
    "location": "[resourceGroup().location]",
    "dependsOn": [
      "[resourceId('Microsoft.Network/virtualNetworks', parameters('virtualNetworkName'))]"
    ],
    "properties": {
      "addressPrefix": "10.0.0.0/24"
    }
  },
  {
    "type": "Microsoft.Compute/virtualMachines",
    "apiVersion": "2020-06-01",
    "name": "[parameters('virtualMachineName')]",
    "location": "[resourceGroup().location]",
    "dependsOn": [
      "[resourceId('Microsoft.Network/virtualNetworks/subnets', parameters('virtualNetworkName'), parameters('subnetName'))]"
    ],
    "properties": {
      "hardwareProfile": {
        "vmSize": "Standard_DS1_v2"
      },
      "storageProfile": {
        "imageReference": {
          "publisher": "MicrosoftWindowsServer",
          "offer": "WindowsServer",
          "sku": "2016-Datacenter",
          "version": "latest"
        },
        "osDisk": {
          "createOption": "FromImage"
        }
      },
      "networkProfile": {
        "networkInterfaces": [
          {
            "id": "[resourceId('Microsoft.Network/networkInterfaces', concat(parameters('virtualMachineName'), '-nic'))]"
          }
        ]
      },
      "osProfile": {
        "computerName": "[parameters('virtualMachineName')]",
        "adminUsername": "adminUser",
        "adminPassword": "adminPassword"
      }
    }
  },
  {
    "type": "Microsoft.Network/networkInterfaces",
    "apiVersion": "2020-06-01",
    "name": "[concat(parameters('virtualMachineName'), '-nic')]",
    "location": "[resourceGroup().location]",
    "dependsOn": [
      "[resourceId('Microsoft.Network/virtualNetworks/subnets', parameters('virtualNetworkName'), parameters('subnetName'))]"
    ],
    "properties": {
      "ipConfigurations": [
        {
          "name": "ipconfig1",
          "properties": {
            "subnet": {
              "id": "[resourceId('Microsoft.Network/virtualNetworks/subnets', parameters('virtualNetworkName'), parameters('subnetName'))]"
            },
            "privateIPAllocationMethod": "Dynamic"
          }
        }
      ]
    }
  }
]

在上面的示例中，"virtualMachineName"参数的值将被用作虚拟机的名称，并在其他资源中引用。例如，在"Microsoft.Compute/virtualMachines"资源中，"networkInterfaces"属性中的"networkInterfaces"数组的元素中使用了"reference"函数来获取网络接口的ID。这个ID使用了"concat"函数来包括了"virtualNetworkName"和"subnetName"参数