最后一个不应该是{joe 13}吗？为何是 {joe 19}？为何进行了值的拷贝？是拷贝哪个值？

package main import ( "fmt" ) type person struct { Name string Age int } func main() { a := person{ Name: "joe", Age: 19, } fmt.Println(a) A(a) fmt.Println(a) } func A(per person) { per.Age = 13 fmt.Println("A", per) } 结果： {joe 19} A {joe 13} {joe 19}