A:电解后溶液质量减少(m+36)g
B:原溶液中Na2SO4的质量分数为 71m161(m+18)
C:若其它条件不变,将石墨电极替换为铜电极,则阴极析出2mol H2
D:若其它条件不变,将石墨电极替换为铜电极,则析出Na2SO4•10H2O晶体仍为m g
如图,梯形ABCD中,CE⊥AD于E,BF⊥AD于F,且AF=BF=BC=1,DE=2,现将△ABF,△CDE分别沿BF与CE翻折,使点A与点D重合.
(Ⅰ)设面ABF与面CDE相交于直线l,求证:l∥CE;
(Ⅱ)试类比求解三角形的内切圆(与三角形各边都相切)半径的方法,求出四棱锥A﹣BCEF的内切球(与四棱锥各个面都相切)的半径.
--I have a cold and my head hurts a lot.
--Oh, sorry to hear that. I hope better soon.
—People near the lake didn't allow them to________ a factory so as not to pollute the water.