Please choose the correct ending to complete the given sentence: Food and Entertaining: [header] How to train your dog to roll over [title] Make sure your dog knows how to lie down. [step] This is an essential first step for completing the roll over trick, since the dog has to be lying down to perform it. If your dog doesn't respond to the " lie down " command, train him to do that first.

Ending1: At the same time, make sure he understands that laying down is very important for its health. [title] Unroll before the roll over trick is completed. Ending2: This way, you can reestablish trust with your dog after the trick has been done, and the power of your command is communicated to him. [substeps] A dog's natural instinct is to chase after food. Ending3: [substeps] You can also start by letting your dog lie on his side. This may help him initially learn to roll over. Ending4: [substeps] If your dog can't roll over, the trick is complete. Just make sure that your dog is lying down on his stomach.

Answer format: ending1/ending2/ending3/ending4