81. The brave men risked their life in trying to save the child.

80. Two thirds of the land in Australia are dry and desert, which is called the outback.

79. He became a brilliant scholar but only on the expense of his health.　

78. The young guy referring to in their talk was involved in serious trouble.

77. Since the late 1960s, everybody in Australia had enjoyed the same rights.

下列每句中有且只有一个错误，请按要求标出错误，并改正。

若多一个词：把多余的词用斜线(\)划掉，在对应横线上写出该词，并也用斜线划掉。

若缺一个词：在缺词处用一个漏字符号(∧),在对应横线上写出该加的词。

若错一个词：在错的词下划一横线，在对应横线上写出改正后的词。

76. The 29^th Olympic Games will lead to strong and powerful China.

75. I’m _____________ (真诚地) thankful for what you did for my family.

74. Of the two choices, I prefer the _____________ (后者).

73. It is still impossible to prove the _____________ (存在) of aliens.

72. This new kind of rice has been _____________ (推广) worldwide.