실내 디자이너가 사무실을 꾸민 뒤 가구 숫자가 적어졌다.

Teacher's answer
- There was less furniture in the office after the interior decorator got done with it.
- There was less furniture in the office after the interior designer was finished with            it/the project.


질문:
1. 학생들이 decorate 이랑reduce 같이쓰면 이상하다고 하셧잔아요. 그러면 만약에 앞에 decorate 단어를 쓰면 뒤에는 the number of furnitures got reduced. 이런 식으로는 써도 디는 건가요?  ex. After the interior designer worked on the office, the number of furniture got reduced.

2. 선생님의 두번째 답중에 interior designer was finished 가 있는데 be verb+ pp 는 passive 잖아요. 그래서 햇갈리더라고요. 선생님이 당연히 맞으실텐데 이 원리가 왜 passive 가 아니라 디자이너가 was finished with it 한건지에 대해서 설명 부탁드려요.