Although there are hundreds of coronaviruses, only ________currently infect humans.
A. ten
B. seven
C. five
D. four
查看答案
Why do we need a new flu vaccine every year?
A. Influenza mutates quickly and new strains result
B. Our bodies rid themselves of the vaccine yearly
C. When it gets warm outside, vaccines do not work anymore
D. Cooler temps often cause vaccines to mutate and not be effective
Corona viruses are a bit different from other RNA viruses. How?
A. They are quite large with many genes.
B. They are usually much more stable.
C. They often have a faster mutation rate.
D. A and B are both answers.
What is it about RNA viruses that makes them more successful than DNA viruses?
A. Smaller and fewer genes.
B. Infect many hosts.
C. Replicates quickly.
D. More likely to mutate.
创业成长需要好的创业种子，创业好种子应该具备哪些要素
A. 美好愿景
B. 人生使命
C. 价值观念
D. 创业精神
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