This is the ring on which she spent 1000 dollars.为什么which前加on?为何这么用?

This is the ring on which she spent 1000 dollars.为什么which前加on?为何这么用? This gold ring is more e_______than the silver one is,on,Linda's,sofa,ring,the连词成句 my mother‘s ring is on the book 同义句 对括号内容提问 the ring is (my mom’s) () () this对括号内容提问 the ring is (my mom’s) () () this ring? is the ring cheap? 英语翻译Look at these things.This is Miss Gao’s ID card.And this is David’s watch,that’s Mary’s key.Gina’s notebook is on the bed.Look!What’s that on the floor?Oh,It’s a gold ring.It’s Grace’s ring.It’s very nine.Look.This is 改错the doorbell is ring The ring is on the table.It's my mother's同意替换 This is my ring.(改为同义句) this is my ring改成同义句 Is this ring red.(作否定句) Is this ring red.(作否定回答) A coral island is very nice to look at.It looks like a ring with trees,grass and flowers on it.one part of the ring is open to the water.Usually there is a little round lake inside the island.If you look into this lake,you will see beautifui carol.Yo Is this your ring?-Yes,this is.哪里错了? ______________be those your parents?This is_________________she gold ring.Here are two_____________photo of my family.Those_________child boats are on the river. this is the real piano on which whose key ring is this?(同意句） whose does this key ring ___ ___