如何将Json字符串转换为c＃中的键值对？

   {
      "transactionId" : XXXXX,
      "uri" : "https://XXX.XXXXXXXX.XXXX/XXX/XXX",
      "terminalId" : 1,
      "action" : "CHARGE",
      "amountBase" : "3.00",
      "amountTotal" : "3.00",
      "status" : "CAPTURE",
      "created" : "2015-01-24T07:24:10Z",
      "lastModified" : "2015-01-24T07:24:10Z",
      "response" : 
       {
           "approved" : true,
           "code" : "00",
           "message" : "Approved",
           "processor" : 
            {
               "authorized" : true,
               "approvalCode" : "XXXX",
               "avs" : 
                     {
                         "status" : "NOT_REQUESTED"
                     },
            }
  },
  "settlement" : 
   {
        "settled" : false
   },
  "vault" : 
   {
        "type" : "CARD",
        "accountType" : "VISA",
        "lastFour" : "1111"
  }

}
   {
      "transactionId" : XXXXX,
      "uri"