一道英文改错题，我被困住了，求高手指点。谢谢。

Question

只允许改10处，每句最多有2处。每处错误仅涉及一个单词的增加、删除或修改。以下是文章。
What are the quality of a good teacher? Let me show you for an example. Mr.Smith,my maths teacher, is one of the best that I ever met.He knows his subject better and he always has special ways to make his classes lively and interested. We are not kept sitting all the time and are encouraging to learn through all kinds of activities. However,he treats all his students equally from the brightest to that who need extra help. I am luckily to have a teacher like Mr. Smith.
希望高手帮帮忙，指点迷津，感激不尽。

Answer 1

1quality 改成 qualities。这里需要用复数。因为做好老师需要的素质不仅仅是一个。
2 for 去掉 show sb sth 不需要介词。
3 maths 改成 math 。math 做形容词用原形。
4 is one of the best that I have ever met.这句加上一个have。 完成时，我所见过的。
5 better 改成 well，这里不存在比较的意思。
6 interest 改成 interesting。 说的是课程有意思。
7 encouraging 改成 encouraged。被动关系 它前面的那半句话也存在被动意思。
8 however改成 furthermore，因为这里说的是更重要的是。。。。，而不是原来的转折关系。
9 that who 改成 those 复数
10 luckily 改成 lucky。这里用形容词。幸运的

Answer 2

What （is） the quality of a good teacher? Let me show you（ for去掉） an example. Mr.Smith,my maths teacher, is one of the best （teachers）that I ever met.He knows his subject （well） and he always has special ways to make his classes lively and （interesting）. We （d0） not （keep） sitting all the time and are （encouraged）to learn through all kinds of activities. However,he treats all his students equally from the brightest to （those） who need extra help. I am（ lucky）to have a teacher like Mr. Smith.

Answer 3

What are the qualities of being a good teacher?
Let me show you an example, my math teacher Mr. Smith is one the the best teacher i have ever met.