当在代理后面使用curl时，
curl -O -fsSL https://storage.googleapis.com/tensorflow-serving-apt/tensorflow-serving.release.pub.gpg -v -k -x http://xxx.xxx.xxx.xxx:8080
我有一个错误，如下所示。我能做什么来解决这个问题？
Trying xxx.xxx.xxx.xxx...
TCP_NODELAY set
Connected to xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx) port 8080 (#0)
Establish HTTP proxy tunnel to storage.googleapis.com:443
CONNECT storage.googleapis.com:443 HTTP/1.1
Host: storage.googleapis.com:443
User-Agent: curl/7.54.0
Proxy-Connection: Keep-Alive
HTTP/1.0 403 Forbidden
Server: squid
Mime-Version: 1.0
Date: Sun, 13 Jan 2019 16:33:30 GMT
Content-Type: text/html
Content-Length: 3149
X-Squid-Error: ERR_ACCESS_DENIED 0
Vary: Accept-Language
Content-Language: en
X-Cache: MISS from unknown
X-Cache-Lookup: NONE from unknown:8080
Via: 1.0 unknown (squid)
Connection: keep-alive
The requested URL returned error: …