I found _________ difficult to solve the crime. [ ]
A. it
B. it's
C. that
D. that it
答案:A
(8分)某温度(t℃)时,水的KW=10-13,则该温度(填大于、等于或小于)
(1)_____25℃,理由是_________________________________________________,将此温度下pH=11的NaOH溶液aL与pH=1的H2SO4溶液bL混合,
(2)若所得混合溶液为中性,则a:b=_________;
(3)若所得混合溶液pH=2,则a:b=__________。
“日暮汉宫传蜡烛,轻烟散入五侯家”。诗中所吟的节日禁火,是为了纪念()(人名)