built newest version, then show wrong info

[rogerBridge]

when I running: go build, it shows:
./main.go:5:2: imported and not used: "net"
./main.go:8:2: imported and not used: "strings",
when I remove related packages, then running: tcping baidu.com, it shows:
Ping tcp://:80 - failed: dial tcp :80: connect: connection refused;

[rogerBridge]

go version: go 1.12.5