A:more, healthier
B:the more, the healthily
C:the more, the healthier
各项均为正数且公差为1的等差数列{an},其前n项和为Sn,则limn→∞Snan·an+1=( )
质量为0.2千克的水温升高50℃,求水吸收的热量Q吸.C水=4.2×103J/(kg•℃).