单选题 1分

There are some possible explanations, but none entirely satisfactory.It could be that there is some ...

There are some possible explanations, but none entirely satisfactory.It could be that there is some
survival value in producing more girls in warmer regions, but it is unclear what this might be.
________72_______that could explain it, but the connection persists over so many varied
populations________73_______.Mice also produce more male offspring during shorter days or colder
weather, but the reasons in these animals are just as mysterious as they are in humans.
“There’s a possibility that _______74________ they were programmed to respond to a long time ago
-not cultural or socioeconomic, but climate and things like latitude,” Dr.Navara said.“What’s interesting
is that we may be seeing something _____75__________.”
  • A.that _______68________us with our animal ancestry
  • B.There may be ________69_______ or racial difference
  • C.humans might be _____70__________ to factors
  • D.that this seems ______71_________