草地鼠灾与下面哪项互为因果( )
A:毁林开荒
B:乱伐森林
C:过度放牧
D:过度抽取地下水
When does Mike usually go to school?
(1)81+-273+-232
(2)(﹣3)2﹣|1﹣3|+22﹣53
(3)求x值:(3x+1)2=16
(4)(x﹣2)3﹣1=﹣28.