以太坊编译找不到 package，求大佬指点

在下 golang 小白，操作完全根据文档，当时总是报错说找不到包，我看网上的教程都是直接安装 golang 后就编译啊，但是我这就不行，不自动下载那些包，非常奇怪。求大佬们指点下。

go 环境

export GOROOT=/usr/local/go export GOPATH=/home/sam/go export PATH$PATH:/usr/local/go/bin sam@ubuntu:~/work/blockchain/go-ethereum$ go version go version go1.12.7 linux/amd64 

下载 go-ethereum 后如下错误

sam@ubuntu:~/work/blockchain/go-ethereum$ make all build/env.sh go run build/ci.go install internal/build/azure.go:25:2: cannot find package "github.com/Azure/azure-storage-blob-go/azblob" in any of: /usr/local/go/src/github.com/Azure/azure-storage-blob-go/azblob (from $GOROOT) /home/sam/work/blockchain/go-ethereum/build/_workspace/src/github.com/Azure/azure-storage-blob-go/azblob (from $GOPATH) build/ci.go:61:2: cannot find package "github.com/cespare/cp" in any of: /usr/local/go/src/github.com/cespare/cp (from $GOROOT) /home/sam/work/blockchain/go-ethereum/build/_workspace/src/github.com/cespare/cp (from $GOPATH) internal/build/pgp.go:27:2: cannot find package "golang.org/x/crypto/openpgp" in any of: /usr/local/go/src/golang.org/x/crypto/openpgp (from $GOROOT) /home/sam/work/blockchain/go-ethereum/build/_workspace/src/golang.org/x/crypto/openpgp (from $GOPATH) common/types.go:31:2: cannot find package "golang.org/x/crypto/sha3" in any of: /usr/local/go/src/golang.org/x/crypto/sha3 (from $GOROOT) /home/sam/work/blockchain/go-ethereum/build/_workspace/src/golang.org/x/crypto/sha3 (from $GOPATH) Makefile:20: recipe for target 'all' failed make: *** [all] Error 1 

感觉自己要崩溃。。。