Please choose the correct ending to complete the given sentence: Health: [header] How to keep a breathing diary for asthma [title] Ask your doctor for a peak flow meter. [step] If you have moderate or severe asthma, your doctor should be able to prescribe a peak flow meter. This device takes a measurement of how fast the air moves out of your lungs.

Ending1: Your doctor should also be able to give you a peak flow chart, which allows you to record your peak flow readings. Insert or copy the chart into your asthma diary. Ending2: Some units may have a recording feature that controls how slow you inhale or exhale. If your meter does not control how fast the air moves, then follow your doctor's instructions. Ending3: [substeps] A peak flow meter measures how fast the air passes out of your body without making it into your lungs. For example, if you have moderate and severe asthma, your doctor will likely be able to give you a peak flow meter. Ending4: Your doctor will measure this rate in milliseconds and give you a time readout. [substeps] Many doctors do not believe that an asthma meter should run out on its own, even if your doctor cannot explain why you are worried.

Answer format: ending1/ending2/ending3/ending4