days while attending a bunch of eggs．Once hatched，tadpoles(蝌蚪)climb on their fathers' backs to be transferred to pools of water．

　　About 10 percent flogs look after their young，and within that group，half to two-thirds rely on males to do the job．For instance，male parental care is not uncommon among the brightly colored Neotropical poison frogs．But in species that have been studied in detail，the males often continue to call to females and mate(交配)while tending eggs，and they spread their attention over several bunches．

　　To learn more about its behavior，Dr．Frogtegur，a behavioral ecologist at Kansas University，caught some smooth guardian frogs and allowed pairs to mate in glass containers．Surprisingly，in all nine instances，the male glued their eyes on the eggs．"They just stationed on or near the eggs，"Dr．Frogtegur said．"I had cameras running 24 hours，and sometimes I suspected they were broken because I couldn't see any movement．"Males also didn't call to females，indicating they could resist the desire to mate．After about 10 days，the males prodded(戳)the eggs，helping the tadpoles inside to spin．Afterwards，they stepped on the eggs to break them．"It's kind of like waking up the children to go to school，"Dr．Frogtegur said．The hatched tadpoles climbed on the males'backs and arranged themselves neatly．He also discovered 10 males carrying their young in the wild．

　　Dr．Frogtegur's study suggests that a rare phenomenon called sex-role reversal(颠倒)may be in play．In such species，females take the initiative(主动)in mating with males often because males never betray their young．

12．What does the author intend to tell us Paragraph 2?

A．Introduce the Neotropical poison frogs．

B．Justify male frogs attending kids．

C．Update us on male flogs' misbehavior．

D．Show smooth guardian flogs' uniqueness．

13．What do we know about Dr．Frogtegur's frog experiment?

A．It shows the health condition of care-givers．

B．It pioneers the theory of sex-role reversal．

C．It stresses the frogs' effect on ecology．

D．It reflects males' "affection" for kids．

14．What can be a suitable title for the text?

A．The role of female frogs． B．A sex-role reversal phenomenon．

C．Unusual mothers' devotion． D．The hatching process of tadpoles．

15．What will be discussed next?

A．More about sex-role reversal． B．Smooth guardian frogs' nests．

C．The growth of hatched tadpoles． D．Energy-efficient way of mating．