听下面一段材料,回答第1至4题。 1. What is the passage mainly about? [ ] A. SARS B. Avian flu C. H1N1 flu 2. How many cases of this virus in the Chinese mainland has reported? [ ] A. 3,577 B. 4,415 C. 10,000 3. How many people died of this flu according to the passage? [ ] A. None B. 20 C. 100 4. Where is the first flu patient at the Huizhou Agricultural School being quarantined (检疫)? [ ] A. At school's clinic B. At home C. In hospital