Whatever/Whichever you decide on, I believe you will do your best

여기서 답이 whatever 인데요 왜 그런가요ㅠㅠwhichever은 안되는건가요??

그리고

When happy and satisfied, cats make soft purring sounds. 에서

When (they are)이 생략되어있던데 When (they) are 이렇게는 쓸수없나요?

또

According to a local newspaper, the witness involved in the bribery case recently has left the country.

에서 involved 에 being 이 생략되어있는거에요???

ㅠㅠㅠㅠ도와주세여 ㅠㅠㅠㅠ