问题
单项选择题 A1型题
很多呼吸道疾病存在周期性流行的现象，其主要原因是（）
A.易感者积累
B.病原体变异
C.疫苗效果不稳定
D.发病率变动
E.病人数量增加
答案
参考答案：A
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很多呼吸道疾病存在周期性流行的现象，其主要原因是（）
A.易感者积累
B.病原体变异
C.疫苗效果不稳定
D.发病率变动
E.病人数量增加
参考答案：A
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| One day Tom was driving a taxi through a busy street. 1 a young man stopped his car and 2 his taxi. "To the station, hurry up!" he said. Tom did his 3 , but at every crossing there was a red light. The young man shouted, "Be 4 ! I don't want to miss the train." Tom shouted back, "I don't want to die here!" At that time he turned back and noticed the young man's face. "Oh , he is 5 thief." He thought, "I saw his face in the newspaper." 6 Tom had an idea. He drove 7 the red light and found a police car running 8 him. "Stop!" The young man said and jumped 9 . Tom caught hold of him and cried." Give me the money!" Just then two policemen came 10 . "He is the thief." Tom said. They caught the young man at once. "You did a good job. Thank you!" the policemen said to Tom. | ||||
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