在使用 Axios 向 FedEx API 发送请求时，需要按照 FedEx API 的文档所示结构来构造参数，并且要确保请求头中包含必要的认证信息。

示例代码：

const axios = require('axios');

const base_url = 'https://ws.fedex.com:443';

async function getRates() {
  try {
    const response = await axios.post(`${base_url}/rate`, {
      "RateRequest": {
        "WebAuthenticationDetail": {
          "UserCredential": {
            "Key": "YOUR_KEY",
            "Password": "YOUR_PASSWORD"
          }
        },
        "ClientDetail": {
          "AccountNumber": "YOUR_ACCOUNT_NUMBER",
          "MeterNumber": "YOUR_METER_NUMBER"
        },
        "TransactionDetail": {
          "CustomerTransactionId": "EXAMPLE_TRANSACTION_ID"
        },
        "Version": {
          "ServiceId": "crs",
          "Major": "28",
          "Intermediate": "0",
          "Minor": "0"
        },
        "ReturnTransitAndCommit": true,
        "RequestedShipment": {
          "DropoffType": "REGULAR_PICKUP",
          "ShipTimestamp": "2022-01-01T08:00:00-08:00",
          "PackagingType": "YOUR_PACKAGING_TYPE",
          "Shipper": {
            "Contact": {
              "PersonName": "YOUR_NAME",
              "CompanyName": "YOUR_COMPANY_NAME",
              "PhoneNumber": "YOUR_PHONE_NUMBER"
            },
            "Address": {
              "StreetLines": [
                "YOUR_ADDRESS_LINE_1",
                "YOUR_ADDRESS_LINE_2"
              ],
              "City": "YOUR_CITY",
              "StateOrProvinceCode": "YOUR_STATE_CODE",
              "PostalCode": "YOUR_POSTAL_CODE",
              "CountryCode": "YOUR_COUNTRY_CODE"
            }
          },
          "Recipient": {
            "Contact": {
              "PersonName": "RECIPIENT_NAME",
              "CompanyName": "RECIPIENT_COMPANY_NAME",
              "PhoneNumber": "RECIPIENT_PHONE_NUMBER"
            },
            "Address": {
              "StreetLines": [
                "RECIPIENT_ADDRESS_LINE_1",
                "RECIPIENT_ADDRESS_LINE