1. My mother will start a [shop] <which(主格) sells children's clothes>.　※[先行詞]
2. Is there [anyone] here <who(主格) can use sign language>?
3. I'll show you some [pictures] (which(目的格：省略可能) I took in Kanazawa).
4. Is that the [girl] <who(m)(目的格：省略可能) you have been waiting for>?　※who/whomどちらでもＯＫ

参考にしてください。