David can't detect ovulation during ovulation

David's undetectable yang could be due to a number of reasons. One possible reason is that a woman's temperature is measured incorrectly. Women should take their temperature at the same time every day and should take the oral temperature by placing the thermometer under their tongue. If these methods are incorrect, the woman may measure wrong body temperature data, causing David to not detect a positive result.

David's inability to detect Yang may also be due to anomalies in the woman's body temperature data. The female menstrual cycle is a very complex process, including changes in body temperature and a series of other physiological processes. If a woman has an abnormality in her menstrual cycle, such as an abnormal cycle or abnormal fluctuations in body temperature, she may not be able to detect ejaculation.

Finally, David’s lack of positive test may also mean that the woman is already in the ovulation period, but the result of David’s test is incorrect. This may be because the woman's temperature data is wrong, or the woman's menstrual cycle is longer or shorter, causing David's test results to be inaccurate.