The first, the view of Western sexologists: the tenth digit of age multiplied by 9, the product of the tenth digit is the time, the single digit is the number of sexual intercourse should have during this period. The second, the Chinese Tang Dynasty medicine king Sun Simiao’s “Thousand Gold Essentials” point of view: the year 20 Sheng, day re-application (twice a day), the deficiency of a day an application; the year 30 Sheng, two days a give, the deficient three days a give; forty Sheng, three days a give, the deficient four days a give; fifty Sheng, five days a give, the deficient ten days a give; sixty Sheng, ten days a give, the deficient twenty days a give; seventy Sheng, thirty days a give, the deficient do not leak. The third, there is love to have sex view: sex – is a “love” of the cause, the rate of sex! Not to “pay the public money”, and not to “complete the task”!