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.

The first two paragraphs suggestthat ____________.

Every animal sleeps,but the reason for thishas remained foggy.When lab rats are not allowed to sleep,they die within amonth. 71One idea is that sleep helps us strengthennew memories. 72 We know that,while awake,fresh memories are recorded by reinforeing (加强)connections between braincells,but the memory processes that takeplace while we sleep have been unclear.  Support is growing for a theory thatsleep evolved so that connections between neurons(神经元)in the brain can be weakenedovernight,making room for fresh memories to from the next day 73 Now we have the most direct evidence yet that he is right. 74 Thesynapses in the mice taken at the end ofa period of sleep were 18 per cent smaller than those taken beforesleep,showing that the connections between neurons weaken while sleeping. If Tononi`s theory isright,it would explain why,when we miss a night`s,we find it harder the nextday to concentrate and learn new information-our brains may have smaller roomfor new experences. Their research also suggests how we may build lasting memories overtime even though the synapscs become thinner.The team discovered that somesynapses seem to be protected and stayed the same size. 75 “You keep what matters,”Tononi says. A. We should alsotry to sleep well the night before. B. Ti’s as if thebrain is preserving its most important memories. C. Similarly, whenpeople go for a few days without sleeping, they get sick. D. The processestake place to stop our brains becoming loaded with memories. E. That’s whystudents do better in tests if they get a chance to sleep after learning. F. “Sleep is theprice we pay for learning,” says Giulio Tononi, who developed the idea. G. Tononi’s teammeasured the size of these connections, or synapses, in the brains of 12 mice.

假设你是红星中学高三学生李华，请根据以下四幅图的先后顺序，写一篇英文周记，记录毕业前夕你们制作以“感恩母校”为主题的毕业纪念视频的全过程。注意：词数不少于60。提示词：视频video

What does theauthor think of the safety problem of super intelligent machines?

Machines withspecific purposes are associated with living things partly because they mightbe able to ???????.

According tosome researchers, we can use firewalls to

Hollywood’s theory that machines with evil(邪恶) minds will drive armies ofkiller robots is just silly. The real problem relates to the possibility thatartificial intelligence(AI) may become extremely good at achieving somethingother than what we really want. In 1960 a well-known mathematician NorbertWiener, who founded the field of cybernetics（控制论）, put it this way: “If we use, to achieve our purposes, a mechanicalagency with whose operation we cannot effectively interfere(干预), we had better be quite surethat the purpose which we really desire.”

What is the purpose of the passage?

Herd immunity works well when ____________.

What is the main reason for thecomeback of measles?

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