某同学向足量的石灰石中加入105.4g稀盐酸,充分反应后过滤,得到含氯化钙10%的溶液111g,则稀盐酸中氢元素的质量分数为( )
A:5.1%
B:10.5%
C:15.7%
D:20.3%
My headache _________ me. I thought it was going away, but now it's getting worse.
下列划线字的注音没有错误的一项是( )
若直线l1:mx﹣y﹣2=0与直线l2:(2﹣m)x﹣y+1=0互相平行,则实数m的值为( )