The outbreak of swine flu that was first detected in Mexico was declared a global epidemic on June 11,2009.It is the first worldwide epidemic 1by the World Health Organization in 41 years.The heightened alert_2 an emergency meeting with flu experts in Geneva that convened after a sharp rise in cases in Australia,and rising 3_in Britain,Japan,Chile and elsewhere.But the epidemic is"4"in severity,according to Margaret Chan,the organization's director general,5 the overwhelming majority of patients experiencing only mild symptoms and a full recovery,often in the 6 of any medical treatment.The outbreak came to global__7 in late April 2009,when Mexican authorities noticed an unusually large number of hospitalizations and deaths 8 healthy adults.As much of Mexico City shut down at the height of a panic,cases began to 9 in New York City,the southwestern United States and around the world.In the United States,new cases seemed to fade 10 warmer weather arrived.But in late September 2009,officials reported there was 11 flu activity in almost every state and that virtually all the 12 tested are the new swine flu,also known as（A）H1N1,not seasonal flu.In the U.S.,it has__13 more than one million people,and caused more than 600 deaths and more than 6,000 hospitalizations.Federal health officials__14_Tamiflu for children from the national stockpile and began 15 orders from the states for the new swine flu vaccine.The new vaccine,which is different from the annual flu vaccine,is 16 ahead of expectations.More than three million doses were to be made available in early October 2009,though most of those 17 doses were of the FluMist nasal spray type,which is not 18 for pregnant women,people over 50 or those with breathing difficulties,heart disease or several other 19.But it was still possible to vaccinate people in other high-risk group:health care workers,people20_infants and healthy young people.12选？
A.categories
B.examples
C.patterns
D.samples