``` func main() { go sing() go dance() for{ ; } } func sing() { for i:=0; i<20;i++ { fmt.Println("sing......") time.Sleep(100 * time.Microsecond) } } func dance() { for i:=0; i<20;i++ { fmt.Println("dance......") time.Sleep(100 * time.Microsecond) } } ```