Here's why:
* Transitive: When "attached" has a direct object, it is transitive. This means it describes an action that is performed on something.
* Example: "I attached the file to the email." (Here, "file" is the direct object)
* Intransitive: When "attached" does not have a direct object, it is intransitive. It describes a state or condition.
* Example: "The two pieces of wood attached securely." (There's no object being attached)
To determine if "attached" is transitive or intransitive in a particular sentence, ask yourself if there's a direct object receiving the action of "attaching."