题干

人感染一次天花就会终生“永志不忘”,再有天花病毒侵入时,能在病毒为患之前迅速将其消灭,这是因为

A:体液中一直保存着针对天花的抗体

B:针对天花的记忆细胞可伴随人一生

C:针对天花的效应T细胞可伴随人一生

D:吞噬细胞可随时“吞食”入侵的天花病毒

上一题 下一题 0.0难度 选择题 更新时间:2019-06-12 03:34:08

答案(点此获取答案解析)

B

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    Do you want to cure all the diseases in the world? It seems like an impossible job, but Priscilla Chan is trying really hard to achieve it.
Chan is a 32-year-old woman from the United States. Many people may know her as the wife of Mark Zuckerberg, the founder of Facebook. But Chan herself has done a lot to help people.
    Chan and Zuckerberg said in September they would give out $3 billion(20 billion yuan) in the next 10 years to help deal with all of the world's diseases. As a doctor, Chan was a big driver in this decision. “We hope that all of our children can live long and healthy lives in the future,” she said.
    Besides health, Chan also cares about children's education. Before becoming a doctor, Chan taught science to fourth and fifth graders at a school in California for a year. This year she started a project called The Primary School. It provides education for children from kindergarten to the twelfth grade.
    Chan herself knows how important education is to a child. She has a Chinese father and a Vietnamese mother. Her parents didn't receive much education. But they worked hard to make sure Chan and their other two daughters would have the best opportunities. Chan went to Harvard University in 2003 and now works as a doctor. “ I realized that I was so lucky to be what I was,” said Chan. “so now, I will try my best to help others. I hope they can also have their opportunities to reach their dreams and be what they would like to be.”