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[史 (限时：25分钟)A If you are afraid of the dark，it's not a big deal.It's perfectly normal to feel afraid. After all，animals do, too. “Fear matters，”says Karen Warkentin，an ecologist.“It's a good thing，” she adds, “because fear makes you do things that keep you alive.”，many animals experience fear and they respond to the feeling in variety of ways.A frightened turtle pulls its head and legs inside its shell.A small fish will swim away when a big，hungry fish approaches.this species，female frogs attach jellylike clumps(果冻一样的块状物)of their eggs to the undersides of leaves.The leaves hang on branches that dangle(悬挂)over ponds.After they hatch from the eggs，the tadpoles(蝌蚪)then fall into the water，where they eventually grow into adult frogs.，however，they can hatch up to 2 days ahead of the schedule. As the snakes are unable to swim，by falling into the water early，the tadpoles can escape.，you might wonder why their eggs don't always hatch sooner.It turns out that hatching early brings its own danger.Once tadpoles land in the water，hungry fish and other animals like to eat them, too.Staying in their eggs for full 6 days，then，allows frog embryos(胚胎)to grow big and strong.This extra growth improves their chances of surviving in the water.________．help animals grow bigger and stronger B．are less common among young animals | 
