Final answer:
Stopping or withholding CPR is acceptable if the rescuer is at risk or too exhausted to continue, and it should be performed after removing the person from the water, emphasizing the need for proper CPR training.
Step-by-step explanation:
Two acceptable reasons to stop or withhold CPR are if the person administering CPR is at risk of harm, or if the rescuer is too exhausted to continue. It's crucial that CPR is only commenced once someone has been removed from the water because it is ineffective in water, and immediate removal and CPR on stable ground is essential. It's important to note that CPR must be performed correctly to avoid injuries such as broken ribs or damage to internal organs. Given this, it is recommended that everyone, especially medical personnel, undergo proper CPR training and certification to ensure they are administering it safely and effectively.