Grown-ups are oftensurprised by how well they remember something they learned as children but havenever practiced still swim as well as ever since.A man when he gets

back who has nothada chance to go swimming for years can in the water. He can get on a bicycleafter many years and still ride away.He can play catch and hit a ball as well

as his son.A motherwho has not thought about the words for years can teach her daughter the poemthat begins"Twinkle,twinkle,little star",remember the story of Cinderella

or Goldilocks andthe Three Bears.

One explanation isthe law of overlearning,which can be stated as follows:Once we have learnedsomething,additional learning trials（尝试）increase the length of time we

will remember it.

In childhood weusually continue to practice such skills as swimming,bicycle riding,and playingbaseball long after we have learned them.We continue to listen to and remind

ourselves of wordssuch as"Twinkle,twinkle,little star"and childhood tales such asCinderella and Goldi-- locks.We not only learn but overlearn.

The multiplicationtables（乘法口诀表）are anexception to the general rule that we forget rather quickly the things that welearn in school,because they are another of the

things we overlearnin childhood.

The law ofoverlearning explains why cramming（突击学习）for an examination, though it may result in a passing grade,is not asatisfactory way to learn a college

course.By cramming,astudent

may learn thesubject well enough to get by on the examination,but he is likely soon toforget almost everything he learned.A little overlearning,on the other hand,isreally

necessary for one'sfuture development.What is theauthor's opinion on cramming?

A.It leads tofailure in college exams.

B.It's helpful onlyin a limited way.

C.It's possible toresult in poor memory.

D.It increasesstudents' learning interest.