单选题 The swine flu will probably return in force earlier than seasonal flu usually begins, federal health officials predicted Friday, saying they expected it to erupt as soon as schools open rather than in October or November.
The swine flu is still circulating in the United States, especially in summer camps, even though hot weather has arrived and the regular flu season ended months ago, "so we expect challenges when people return to school, when kids are congregating together," Dr. Anne Schuchat, director of respiratory diseases at the Centers for Disease Control and Prevention, said in a telephone news conference held jointly with vaccine experts from the Food and Drug Administration and the Department of Health and Human Services.
It is still unclear how many doses of a swine flu vaccine will be available by then, and officials have been reluctant to make firm predictions beyond saying that they expect tens of millions, rather than hundreds of millions, and they plan to distribute them to people who are the most vulnerable, like pregnant women and people who are the most likely to encounter the flu, like health care workers.
The number of doses available will depend on how fast seed strains grow, how much protection a small dose provides, and whether immune-system boosters called adjuvants are needed and prove to be safe; adjuvants are not used in American flu vaccines now.
Clinical trials testing those questions are expected to take another couple of months, said Dr. Jesse L. Goodman, director of the F. D．A．'s Center for Biologics Evaluation and Research.
Assuming a swine flu vaccination campaign begins, it will be voluntary, Dr. Schuchat emphasized, but she "strongly encouraged" pregnant women to get both a seasonal flu shot and a swine flu shot when they are available.
The C．D．C．has been closely following the disease in the Southern Hemisphere winter, and it is mimicking the patterns seen in the United States and Mexico in the spring, she said.
Most infections and most serious cases are in children and young adults, and those with underlying conditions, including pregnancy, are the most likely to die. Dr. Schuchat likened the spread's unpredictability to that of popcorn: one city could see an explosion of cases and overwhelmed hospitals while another saw few.
Her most important message, she added, was that "the virus isn't gone, and we fully expect there will be challenges in the fall. /

单选题 Why did officials expect the swine flu to erupt as soon as schools open rather than in October or November?
【正确答案】 B
【答案解析】重点在于第二段第一句，即“甲型H1N1流感目前仍在美国流行，特别是在夏令营中”。由于流感多在人群密集地方爆发，故学校一开学，流感就很有可能再度爆发。选项C、D文中未提及，而选项A虽在下文中有提及，但却并未说到时候是否会有足够的疫苗。
单选题 What measures will be taken due to the potential insufficiency of swine flu doses?
【正确答案】 C
【答案解析】根据第三段作答。第三段，政府官员表示并不清楚到时会不会有足够的疫苗可用，故要先分配给最急需的人。选项A、B、D逻辑上并无错误，但在文中并未提及，故不选。
单选题 According to the text, what does "adjuvant" (Para 4, Line 2) refer to?
【正确答案】 A
【答案解析】参照文中的“immune-system boosters called adjuvants”这一部分即可作答。
单选题 Which of the following questions is not included in "those questions" (Para 5, Line 1) ?
【正确答案】 D
【答案解析】综合上段内容，可以看出指代的是上段中how fast seed strains grow，how much protection a small dose provides，以及whether immune-system boosters called adjuvants are needed and prove to be safe这三个问题。故答案为D。
单选题 Which of the following is the most infective to this disease?
【正确答案】 A
【答案解析】重点在于倒数第二段的第一句“Most infections and most serious cases are in children and young adults，and those with underlying conditions，including pregnancy，are the most likely to die．”这里所说的是青少年、身体虚弱以及怀孕的，那么再综合选项考虑即可得出答案为A。