The secret to happiness is keeping busy, research by Professor Christopher has found. Keeping the mind 　48　 with tasks--- no matter how meaningless---can keep away from 　49　 emotions. But humans seem born to be lazy in order to save 　50　 .

In a study each student was given a choice of handing in a survey nearby or at a more distant 　51　 they had to walk to. The findings showed that the students who had taken the walk felt happier.

At the individual level, he advised: “Get up and do something, 　52　 there really is no point to what you are doing.” Then he 　53　 : “Incidentally, thinking deeply or engaging in self-reflection 　54 as keeping busy. You don’t need to be running around---you just need to be engaged, either physically or 　55　 .”

48.A.carried 　　　　　　　　 B. occupied　　　　　　　　　 C. burdened 　　　　　　　　 D. crowded

49.A.aggresive　　　　　　　 B. ordinary　　　　　　　　　　 C. negative 　　　　　　　　　 D. changeable

50.A.money　　　　　　　　　 B. life　　　　　　　　　　　　　 C. resource　　　　　　　　　 D. energy

51.A.location　　　　　　　　 B. situation　　　　　　　　　　 C. direction　　　　　　　　　 D. occasion

52.A.as if 　　　　　　　　　　 B. even if 　　　　　　　　　　 C. as long as 　　　　　　　　 D. now that

53 A. discovered 　　　　 B. claimed　　　　　　　　　　 C. predicted　　　　　　　　　 D. added

54.A.counts B. benefits C. stresses 　　　　　　　　　 D. influences

55 A. generally　　　　　　　 B. mentally 　　　　　　　　　 C. usually　　　　　　　　　　　 D. normally