the man told me to oil it and i bought it from him.

-the man from whom i bought it told me to oil it.
-the man who(m) i bought it from told me to oil it.
-the man i saw me to come today.
-the man i bought it from told me to oil it.

이 네가지 경우가 다 가능한거죠?

특히 세번째께 걸리네요ㅠㅠㅠㅠthe ladder on which i was standing began to slip.
the ladder i was standing began to slip on the ladder.
the ladder (which) i was standing on began to slip.

여기에서 the ladder i was standing began to slip.

위에서처럼 다 전치사 + 관계대명사 다 생략할 수 있나요?