题型:选择题 Once he has decided to do something,he’ll never give up______.[ ]A.no matter how it is hard B.however is it hardC.no matter how hard it is D.however hard is it 查看答案
题型:选择题 有关荒漠化成因的说法,错误的是( )A.荒漠化是人类过度的经济活动和潜在的自然因素相互影响、共同作用的产物B.气候因素中,气温的变化对荒漠化进程影响最大C.人类活动在荒漠化发生和发展过程中起着决定性作用D.植被退化和覆盖率降低是荒漠化的前兆 查看答案