51、public event=communal activity

52、aviation disaster=sky accident=air crash

53、resemble=like=similar=alike=comparable

54、weather=meteorological=climate=condition

55、create=establish=invent=start up=open=set up

56、improve=develop=evolve=catch up=pick up

57、average-sized=medium-sized

58、remain=stay=keep=continue to be=still

59、documentation=written account=evidence=proof

60、shift=switch=transfer=move=jerk

61、drought=no rain at all=dry=dusty

62、period=cycle=era=age

63、pattern=trade / commodity=business

64、unappreciated=undervalued

65、study=research=analyse=do/conduct research

66、smell=odour=scent

67、define=distinguish=tell the difference

68、to be defined=unanswered

69、linguistic=language

70、do not smell=odorless

71、certain=some=a measure of

72、building=property=construction

73、financial support=fund=financial aid

74、create=generate=form=produce

75、beam=laser=ray=glow=glare

76、aim=purpose=point=idea=objective=goal

77、inherit=run in family=receive=get=be given

78、lessen=minimize=subside=lighten=relieve

79、inexorable=inevitable=unstoppable

80、biological clock=internal clock