75. At first my new ________(环境) were difficult to tolerate.

74. For convenience, it is divided _________( 大约 )into three zones.

73. The southern part of Ireland was unwilling and _________(脱离) away to form its own government.

72. He found that it came from the river __________( 污染 )by the dirty water from London.

71.John Snow wanted to face the _____________( 挑战 ) and solve this problem.