单步式利润表的格式为（）的账户式结构。
A、上下加减
B、左右加减
C、上下对照
D、左右对照
参考答案：D
Evidence has been found through years of study ________ children's early sleeping problems are
likely to continue when they grow up. [ ]
A. why
B. how
C. whether
D. that
在450千克水中加入50千克的盐．求盐水的含盐率．
