题目内容：

 

C

New York City was dealing with a growing public health threat Sunday after tests confirmed (证实) that eight students at a private Catholic high school had contracted（感染）the same strain of the AH1N1 flu that has ravaged (重创) Mexico . Some of the school’s students had visited Cancun on a spring break trip two weeks ago .

Officials reported 68 U.S. cases of AH1N1 flu in five states so far , with the latest in Ohio and New York . Unlike in Mexico , cases in the United State have been mild – and U.S. health authorities can’t yet explain why .

In New York City , Centers for Disease Control and Prevention confirmed that there were 45 cases , Mayor Michael Bloomberg said .

About 100 students at St. Francis Preparatory School complained of flu-like symptoms(症状) ; further tests will determine how many of those cases are AH1N1 flu. St. Francis is the largest private Catholic high school in the nation , with 2, 700 students . The school canceled classes on Monday and Tuesday in response to the outbreak .

Bloomberg stressed that the New York cases were mild and many are recovering , but said that some family members of students also had flu symptoms .

In Mexico , health officials say a strain of AH1N1 flu has killed up to 160 people and sickened over 2, 000 . New York officials said the flu strain discovered in the patients here is the same strain as in Mexico , though all the New York cases are mild .

AH1N1 flu is a respiratory (呼吸道) disease of pigs caused by type A flu viruses . Human cases are uncommon but can occur in people who are around pigs . It also can be spread from person to person . Symptoms include a high fever , body aches , coughing , sore throat and respiratory congestion .

49.The passage seems to suggest that _________ .

New York City hasn’t done enough to prevent the disease

the AH1N1 flu in the U.S. likely came from Mexico

people appear to have immunity (免疫力) to the virus

children are likely to be infected with the AH1N1 flu

50. What did St. Francis do in response to the outbreak ?

A. The school called off courses .

B. The school handed out masks to every student .

C. The school planned another trip to Cancun .

D. The infected students were required to stay at home .

51.Compared with cases in the U.S. cases in Mexico are _________ .

A. milder      B. more typical     C. more severe      D. more gentle

52. Which is the main idea of the article ?

A. AH1N1 flu is spreading quickly globally .

B. Many people died of AH1N1 flu in Mexico

C. How does AH1N1 flu spread ?

D. AH1N1 flu is confirmed in New York City