It is an island which name I have forgotten.这句话哪里有错?

It is an island which name I have forgotten.这句话哪里有错?
It is an island which name I have forgotten.这句话哪里有错?

It is an island which name I have forgotten.这句话哪里有错?
which-whose

这是一个强调句接一个定语从句，前面强调主语，应将which改为that,后面的定语从句，是修饰宾语的，关系代词可省略