81．C There is a variety of expressions of appreciation

82．B Thanks

83．D Sure

84．A Gender

85．C show their gratitude to others

86．B had great impact on American's work and life

87．D couldn't sell their home in Big Lake

88．A Cindy had seen the benefits of gardening in a different way．

89．C built up family ties and kid's enthusiasm

90．B It gave her confidence and optimism

91．D emphasize the sharp contrast between now and then

92．A pessimistic

93．D mildly critical of

94．B parents and children feel equally disappointed

95．C graduate unemployment is both a political and social issue

96．A awe

97．C the mummy was found lying right inside the stone coffin

98．B quiet

99．A gigantic structure，great desert expanse

100．B objective．