When David's ovulation test paper appears strong positive, it indicates that it is in the ovulation period. In clinical, ovulation test is to detect luteinizing hormone in urine. When strong () appears, it indicates that luteinizing hormone has reached a peak in the body, indicating that ovulation will occur about 24-48 hours after the body reaches this peak. When strong () is detected with ovulation test paper, it is recommended to choose the same room 24 hours later, so that the chance of pregnancy will be improved. In addition, in clinical practice, if there is no strong () detected by ovulation test paper, it is recommended to monitor ovulation by B-ultrasound.. Be sure to find a strong positive 24 hours later and then have sex, so in clinical practice it will increase the probability of pregnancy. If no strong positive result is found during the test, there may be no ovulation in clinical practice. It is suggested that ovulation can be monitored through B ultrasound.