解方程组

（Ⅰ） ；（Ⅱ） $\{\begin{array}{c}\text{x+}2\text{y-z=}6\\ 2\text{x+y+z=}9\\ 3\text{x+}4\text{y+z=}18\end{array}$

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。

    Living without an aim is like sailing without compass. If there is no aim, we will get lose. Last term, I couldn't accept the truth which I failed in my math examination. I decided to give it up, so I skipped from classes frequently. Considered my case, my teacher offered me several detailed approach and advised me to set a short-term goal to improve my math. Finally, I work harder than ever and made great progress in her math. In my opinion, success lies in a series of goals. However, we should remember to make our targets clearly and try our best to realize our dreams.

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