单细胞生物不仅依靠一个细胞完成各种生命活动，也能对周围环境变化作出反应．（判断对错）

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。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 Sir/Madam,

    I'm one of your customer. I ordered a set of books on your website two weeks ago, but I didn't received it until yesterday. And much to my disappointment, the books were too poorly packed up that the cover of one book were torn. To make matters worse, it is not a complete set, as I found one book missed.

    I'm sorry to have received such poorly service, and I believe I have every right ask you to deal with this problem. I hope you either return my money back or deliver a new set of books to me. Beside, I'd like to be informed of the process of your deal with my complaint.

    I'm looking forward to your reply.

Li Hua

已知非零向量$\overrightarrow{AB}$与$\overrightarrow{AC}$满足$(\frac{\overrightarrow{AB}}{\left|AB\right|}+\frac{\overrightarrow{AC}}{\left|AC\right|})·\overrightarrow{BC}=0$且$|\frac{\overrightarrow{AB}}{\left|\overrightarrow{AB}\right|}·\frac{\overrightarrow{AC}}{\left|\overrightarrow{AC}\right|})=\frac{1}{2}$则$△ABC$为（ ）