1.Could not resolve host: mirrors.cloud.aliyuncs.com; Unknown error"
解决方法：
进入 vim /etc/resolv.conf
修改成：
ptions timeout:2 attempts:3 rotate single-request-reopen
; generated by /usr/sbin/dhclient-script
nameserver 100.100.2.136
nameserver 100.100.2.138
nameserver 8.8.8.8
nameserver 8.8.4.4
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