亲子间的相似性称为______．亲子间和子代个体间的差异称为______．

     Bringing a giraffe into the world is a tall order．A baby giraffe falls 10 feet from its mother's
womb (子宫) and usually lands on its    1_．Within seconds it rolls over and tucks(缩拢) its legs
under its body．Gary Richmond describes how a newborn giraffe learns it first   2   in his book,
A View from the Zoo．
     The mother giraffe   3   her head long enough to take a quick look．Then she   _4   herself
directly over her calf．She waits for about a minute, and then she does the most   5   thing．She
swings her long leg outward and kicks her baby．
     If the baby giraffe doesn't   6   , the violent process is repeated over and over again．The   _7  
to rise is very important．As the baby calf grows   8   , the mother kicks it again to stimulate(激励)
its efforts．Finally, the calf stands for the first time on its   9   legs．
     Then mother giraffe does the most remarkable thing．She kicks it off its feet again．  10   ?
She wants it to remember how it got up．In the wild, baby giraffes must be able to get up as    11  
as possible to stay with the herd(鹿群), where there is   12   ．Wild animals and hunting dogs all   13 
young giraffes, and calves would be punished if the mother didn't   14   her calf to be watchful and
get up quickly．
     Irving Stone   15   this．He spent a lifetime studying   16   , writing novelized biographies of
such men as Michelangelo, Vincent van Gogh, and Charles Darwin．
     Stone was once asked if he had found a   17   that runs through the lives of all these exceptional
people．He said, "They are   18  over the head, knocked down, and for years they still get   19  ．
But every time they are knocked down, they stand up．You cannot   20   these people.And at the
end of their lives they've accomplished some modest part of what they set out to do．