Every Monday morning, 73-year-old Li Lanjuan sits in her office, receiving patients. Despite being leading figure in epidemiology（流行病学） in China, Li regards herself as an ordinary medical worker. So when the novel coronavirus（新冠肺炎） broke out in late December, Li, without any hesitation, joined the epidemic expert group on Jan 18 and headed for Wuhan to fight against the disease. As soon as the team found that the new virus can be passed from person to person, Li bravely proposed that Wuhan should be immediately locked down. At that time, experts still knew little about the novel coronavirus' spread; Li's proposal indicated that a city with over 11 million population would be in a dangerous status. If her judgment was incorrect, both the city and Li's reputation would suffer greatly. But Li cared about nothing more than millions of people in the city and the whole nation. She handed her proposal to the government again. It was adopted the next day and proven to be effective later. Yet it was only the beginning of the battle. Since she arrived in Wuhan, Li has been working nonstop. "We can bring our experience to Wuhan and we hope that seriously ill patients can be treated in a timely manner,“ she said. But constant work has done great harm to Li, giving her very little time to sleep. When a picture of her exhausted face was posted on the Internet, many Internet users she tears, expressing concerns about her health. One wrote, "Li is a real herd who has devoted herself to public health." But Li smiled and said,"I'm in good health", and continued to "race against time". Any job well done must have been carried out by a person who is fully devoted. Li has been fully committed to her job. No wonder many call her "a female fighter on the frontline".