Keep variable name consistency

zh/02.6.md

@@ -142,7 +142,7 @@ interface类型定义了一组方法，如果某个对象实现了某个接口
 		mike := Student{Human{"Mike", 25, "222-222-XXX"}, "MIT", 0.00}
 		paul := Student{Human{"Paul", 26, "111-222-XXX"}, "Harvard", 100}
 		sam := Employee{Human{"Sam", 36, "444-222-XXX"}, "Golang Inc.", 1000}
-		Tom := Employee{Human{"Tom", 37, "222-444-XXX"}, "Things Ltd.", 5000}
+		tom := Employee{Human{"Tom", 37, "222-444-XXX"}, "Things Ltd.", 5000}
 
 		//定义Men类型的变量i
 		var i Men
@@ -154,8 +154,8 @@ interface类型定义了一组方法，如果某个对象实现了某个接口
 		i.Sing("November rain")
 
 		//i也能存储Employee
-		i = Tom
-		fmt.Println("This is Tom, an Employee:")
+		i = tom
+		fmt.Println("This is tom, an Employee:")
 		i.SayHi()
 		i.Sing("Born to be wild")