2. 外语
  3. There are about 105 males born for every 100 females, but this (36)______ drops to near balance at the age of maturity, and amon

There are about 105 males born for every 100 females, but this (36)______ drops to near balance at the age of maturity, and amon

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问题     There are about 105 males born for every 100 females, but this (36)______ drops to near balance at the age of maturity, and among 70-year olds there are twice as many women as men. But the great universal of male (37)______ is being changed. Now, boy babies (38)______ almost as well as girls do. Fifty years ago, the chance of a baby(particularly a boy baby)surviving depended on its weight. A kilogram too light or too heavy (39)______ almost certain death. Today it makes almost no (40)______. Since much of the variation is due to genes, one more agent of evolution has gone.
    There is another way to (41)______ evolutionary suicide: stay alive, but have fewer children. Few people are as (42)______ as in the past. Nowadays the number of births, like the age of death, has become (43)______. Again, (44)____________.
    For us, this means that evolution is over; the biological Utopia has arrived. Strangely, it has involved little physical change. No other species fills so many places in nature. (45)____________ .We did not evolve, because machines and society did it for us. Darwin had a phrase to describe those ignorant of evolution: they "look at an organic being as a savage looks at a ship, as at something wholly beyond his comprehension." No doubt we will remember a 20th century way of life beyond comprehension for its ugliness. (46)____________.

  
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答案differences between people and the opportunity for natural selection to take advantage of it have diminished
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