C

Measles(麻疹), which once killed 450 children each year and disabled even more,was nearly wiped out in the United States 14 years ago by the universal use ofthe MMR vaccine(疫苗). But thedisease is making a comeback, caused by a growing anti-vaccine movement andmisinformation that is spreading quickly. Already this year, 115 measles caseshave been reported in the USA, compared with 189 for all of last year.

The numbers might sound small, but they arethe leading edge of a dangerous trend. When vaccination rates are very high, asthey still are in the nation as a whole, everyone is protected. This is called“herd immunity”, which protects the people who get hurt easily, including thosewho zxxk can’t be vaccinated for medical reasons, babies too young to getvaccinated and people on whom the vaccine doesn’t work.

But herd immunity works only when nearly thewhole herd joins in. When some refuse vaccination and seek a free ride,immunity breaks down and everyone is in even bigger danger.

That’s exactly what is happening in smallneighborhoods around the country from Orange County, California, where 22measles cases were reported this month, to Brooklyn, N.Y., where a 17-year-oldcaused an outbreak last year.

The resistance to vaccine has continued fordecades, and it is driven by a real but very small risk. Those who refuse totake that risk selfishly make others suffer.

Making things worse are state laws that makeit too easy to opt out(决定不参加) of what are supposed to be required vaccines for all childrenentering kindergarten. Seventeen states allow parents to get an exemption（豁免), sometimes just by signing apaper saying they personally object to a vaccine.

Now, several states are moving to tightenlaws by adding new regulations for opting out. But no one does enough to limitexemptions.

Parents ought to be able to opt out only forlimited medical or religious reasons. But personal opinions? Not good enough.Everyone enjoys the life-saving benefits vaccines provide, but they’ll existonly as long as everyone shares in the risks.

63．The first two paragraphs suggestthat ____________.

A．a small number of measles cases can start a dangerous trend

B．the outbreak of measles attracts the public attention

C．anti-vaccine movement has its medical reasons

D．information about measles spreads quickly

64．Herd immunity works well when ____________.

A．exemptions are allowed

B．several vaccines are used together

C．the whole neighborhood is involved in

D．new regulations are added to the state laws

65．What is the main reason for thecomeback of measles?

A．The overuse of vaccine.

B．The lack of medical care.

C．The features of measles itself.

D．The vaccine opt-outs of some people.

66．What is the purpose of the passage?

A．To introduce the idea of exemption.

B．To discuss methods to cure measles.

C．To stress the importance of vaccination.

D．To appeal for equal rights in medical treatment.