科学认识发生和发展的动因有两个方面，一是存在于科学外部的，是社会的（）需要；二是存在

短文改错。

     下面短文中有10处语言错误。请在有错误的地方增加、删除或修改某个单词。

增加：在缺词处加一个漏字符号（∧），并在其下面写上该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写上修改后的词。

注意：1. 每处错误及其修改均仅限一词。 

          2. 只允许修改10处，多者（从第11除起）不计分。

     I was playing at my cousin house. Since his family was rich than mine, he had more toys than I did.

There was one on particular I'd always wanted. I put into my pocket when he wasn't looking. I guessed,

even at that age, I would never be able to enjoy to playing with the toy or faced my cousin again; I would

always know I'd done something wrong. Late on, my aunt drove me home. When she dropped me off, I

pulled out the toy slow and gave it back. She knows what had happened, but she thanked me and ever

mentioned it again.

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计算题：已知n（CO₂）=0.5mol，以CO₂为基本单元，问m（CO₂）=？（相对原子质量：C=12，O=16）

若关系模式R的规范化程度达到4NF，则R的属性之间不存在非平凡且非______的多值依赖。

某常规项目（IRR唯一），当i₁=12%时，净现值为860万元；当i₂=18%时，净现值为-600万元。基准收益率为10%，则该项目的财务内部收益率应（）。

A.在12%和10%之间

B.小于12%

C.在12%和18%之间

D.大于18%

下面哪一种内存条的频率是最高的（）。

A.SDR

B.DDR

C.RDR

D.EDO