根据句子内容和汉语提示，用所给词的正确形式填空（一空一词，每题1.5分，共15分,请把正确的词写在答卷纸上）
71. John Snow wanted to face the _____________( 挑战 ) and solve this problem.
72. He found that it came from the river __________( 污染 )by the dirty water from London.
73. The southern part of Ireland was unwilling and _________(脱离) away to form its own government.
74. For convenience, it is divided _________( 大约 )into three zones.
75. At first my new ________(环境) were difficult to tolerate.
76.  These carriages float above the ground and by bending or _________(按，压) down in your seat.
77. We are __________(高兴的) you are coming to work with us.
78.  __________(与此同时) you have to prepare the next question depending on what the person says.
79. The functions of your skin are also very __________(复杂的).
80.  You can get burned by a _________(多样) of things: hot liquids, steam, fire, radiation ect.