except的一些问题His composition is good,________ some spelling mi

except的一些问题
His composition is good,________ some spelling mistakes.
mistake和composition是不同类的,用except for我知道.
但问一下能用excepting吗?
The pair of trousers fits me well ________ the waist of it is a little too small.
裤子和腰不是不同类吗,为什么用except?
Key:
except for except