短文改错

假如英语课上老师要求同桌之间交换修改作文，请你修改你同桌的以下作文，文中共有10处语言错误，每句中最多有两处。每处错误仅涉及一个单词的增加，删除或修改。

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

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处起）不计分。

Dear Editor,

    I used to be a physician in the children's department of a hospital. From time to time I treated children who had poisoned by medicine with older family members. The children didn't know the medicine was danger; they just knew it tasted sweet. Children easily open the bottle what we now use in China.

    Some days before I talked about medicines with an American. He showed me a sort of plastic bottle. The design was quite simple and I'm sure our Chinese factories could produce these bottles. The top of the bottle can be opened by pressing down on them while turning, which is difficult for most young children to do so, though grown-up can open these bottles very easily.

    I'm certainly that the expense of making such tops would be very small. As a doctor, I'd love to see this doing. And most parents would be grateful.

Sincerely yours

Li Hua

红方是腐乳的一种．请回答与其制作有关的问题：

（1）补充制作红方的实验流程：①____ →②加盐腌制_③____ →④密封腌制．

（2）在实验流程①中，首先将豆腐块平放在笼屉内，笼屉中的温度应控制在____ ℃，并保持在一定的____ ．5天后豆腐块表面布满毛霉菌丝，这些毛霉来自空气中的____ ．

（3）在实验流程②操作中，向长满毛霉的豆腐块加盐，其作用是析出豆腐中的水分，使豆腐块变硬．同时，盐还能____ ，避免豆腐块腐败变质．

（4）在实验流程③用到的辅料中，卤汤是由____ 及各种____ 配制而成的．此外，红方因加入了____ 而呈深红色．

例：那只灰雀在枝头歌唱。

那只胸脯深红的灰雀欢蹦乱跳地在枝头歌唱。

①妈妈在公园里散步。

②我们跟着老师去春游。

下列命题中，真命题的个数有   （   ）
①$\forall x\in R,x^2-x+\frac{1}{4}\ge 0$；
②$\exists x>0,\ln x+\frac{1}{\ln x}\le 2$；
③“$a>b$”是“$a{c}^2>b{c}^2$”的充要条件；
④$y=2^x-2^{-x}$是奇函数.