分析原因：
域名解析失败，这可能是与DNS服务器地址有关，通过命令：sudo gedit /etc/resolv.conf ，查看DNS地址为：nameserver 127.0.1.1。整个文件为：
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
search localdomain
解决方法：
在windows环境下打开cmd，输入：ipconfig /all得到主机的DNS地址：
然后将主机的DNS地址加入到resolv.conf文件中，更改后如下：
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 127.0.1.1
nameserver 202.117.0.20
search localdomain
然后重启虚拟机即可