"Comrade Li Yuan, please explain the mechanism behind women's menstruation.",Li Yuan looked up at the sky. Two days ago, a sandstorm swept through the capital city, covering everything in a layer of yellow sand. But the sky was still a refreshing blue, making people feel clear-headed and invigorated.,I muddled through and reached the age of thirty-five before finally saving enough for a down payment on a new apartment in a fifth-tier city.。