如何在Golang中使用Append方法。 语法要求接口？

I am using the Split method to retrieve the words from two separate strings (str1 , str2) and append all together in another Array (str)

package main
import (
 "fmt"  
 "strings" )

func main() {

Name := "Red Blue Green"
Address := "New York Paris France"

str1  := strings.Split(Name, " ")
str2  := strings.Split(Address, " ")
str   := append(str1 , str2)

fmt.Println(str)

}

I am getting the error :

cannot use str2 (type []string) as type string in append

Go Playground Link :

Can anyone help me with this? I am a beginner at this.

Thank You.