A:1mol H+含有的电子数
B:标准状况下,22.4L酒精所含的分子数
C:1.6 g CH4 含有的质子数
D:1L 1mol/L的硫酸钠溶液所含的Na+ 数
在△ABC中,A=45°,AC=4,AB=2,那么cosB=( )
There are fewer and fewer tigers in India. The situation will continue ______ humans stop hunting them for their fur and bones.