2)오늘 저는 책을 잊었네요. Today, I forgot my book.
This sentence is correct but I recommend that 오늘 저는 책을 <font style="background-color: yellow;">잊었어요. 잊어버렸어요. 깜빡했어요</font>=forgot
3)<strike>자</strike><font style="background-color: yellow;">저</font>는 키를 잃었네요.<font style="background-color: yellow;"> (or 잃어버렸어요. 잃었어요)</font> I lost the key.
4)<strike>귀엽이라서</strike> <font style="background-color: yellow;">귀엽기때문에</font> 저는 고양이<strike>를 있아요 </strike><font style="background-color: yellow;">가 있어요</font>.. Because they are cute, I have a cat.
In Korean, 'have a animal' same mean 'raise a animal', 기른다. so It is more nature '저는 고양이를 키웁니다/기릅니다.'
5)<strike><font style="background-color: yellow;">피군이라사</font></strike>피곤해서 <strike>자</strike><font style="background-color: yellow;">저</font>는 커피<font style="background-color: yellow;">가</font> 필요<font style="background-color: yellow;">해요</font>. Because I am tired, I want coffee.
6)좁은이라서 여자는 사다리를 사용하여요. Because she is short, the woman uses a ladder.
<font style="background-color: yellow;">(키가) 작아서 그 여자는 사다리를 사용한다.</font>
7)<strike>자</strike><font style="background-color: yellow;">저</font>도 꽃<font style="background-color: yellow;">(밭)</font>을 심으려고해요 . I also intend to plant a flower garden.
8)내일 제(v) 양탄자를 닦으려고해요. Tomorrow I intend to clean my carpet. ----->perfect!
9)오늘 <strike> 공용젼을</strike><font style="background-color: yellow;">수도꼭지를</font> 수리하려고해요. Today I intend to fix the faucet.
Your Korean is very good! I want to using on other language like as you!
