There are two ways to tell if the timing belt has been replaced. One is obvious-you are looking at a service receipt showing the replacement.
Swimlane diagrams are used whenever you need to show activities, tasks, or process steps which are being performed by different actors/roles. You can use swimlanes to group activities in an activity diagram or process flow by any category what you need: by role, by system, by department, etc.
The pneumatic duct is a tube that runs between the esophagus and the swim bladder. Goldfish may gulp and burp air to alter the pressure in the swim bladder. It is unclear to what degree they actually use burping and gulping to decrease or increase the pressure in the swim bladder.