1a) (C. E.)This is the picture which caused such sensation; The stairs which lead to the cellar are rather slippery. This is the picture that caused such a sensation; The stairs that lead to the cellar are rather slippery.
[Con antecedente «cosa» y en función sujeto las formas del pronombre relativo que se emplean son «which» y «that.» «which» es la más formal.]
1b) (C. no E.) The block, which cost L5 million to build, has been empty for years; The 8:15 train, which is usually very punctual, was late today. The block cost L5 million to build and has been empty for years. The 8:15 train is usually puntual; but it was late today.
[El único pronombre relativo a usar es «which.» «that» no se emplea. En lenguaje conversacional se prefiere reemplazar esta claúsula relativa con antecedente «cosa» y el pronombre relativo en función sujeto por oraciones coordinadas («The block cost L5 million to build and has been empty for years.»)]
2a) The car which I hired broke down; the car that I hired broke down; the car I hired broke down. All the apples that fall are eaten by the pigs. This is the best hotel (that) I know.
[Con antecedente «cosa» y en función objeto los pronombres relativos que se usan en las claúsulas especificativas son «which» o «that» o total omisión del relativo («The car which I hired …»; «The car that I hired …»; «The car I hired …»). «which» no se usa a continuación de «all,» «everything,» «little,» «much,» «none» y compuestos de «no», o después de superlativos. En su lugar se usa «that» («All the apples that fall are eaten by the pigs»), o se prescinde del relativo, si este es el objeto de un verbo («This is the best hotel I know.»)]
2b) (C. no E.) She gave me this jumper, which she had knitted herself; She gave me this jumper; she had knitted it herself. These books, which you can get at any bookshop, will give you all the information you need; These books will give you all the information you need. You can get them at any bookshop. This machine, which I have looked after for twenty years, is working perfectly; Your inefficiency, which we have put up with far too long, is beginning to annoy our customers.
[El único pronombre relativo usado como objeto es «which.» «that» no se usa y «which» no puede omitirse. Cuando «which» aparece como objeto de verbos frasales como «look after,» «look forward to,» «put up with» hay que tratarlos como una unidad, i. e. la preposición/adverbio no debe quedar separada del verbo.]
3a) (C. E.) The ladder on which I was standing began to slip. The ladder which I was standing on began to slip; The ladder that I was standing on began to slip. The ladder I was standing on began to slip.
[La construcción formal es ‘ «preposición» + «which» ‘ pero lo habitual es trasladar la preposición al final de la claúsula usando «which» o «that» o prescindiendo del relativo.]
3b) (C. no E.) Ashdown Forest, through which we’ll be driving, isn’t a forest any longer; Ashdown forest, which we’ll be driving through, isn’t a forest any longer. His house, for which he paid L 10.00, is now worth L 50.000; His house, which he paid L 10.000 for, in now worth L 50.00.
[La preposición va delante de «which» o, más informalmente al final de la claúsula.]
4a) (C. E.) a house whose walls were made of glass. a house with glass walls.
[Con antecedente «cosa» y en función de posesivo se puede emplear ‘ «whose» seguido de claúsula ‘ pero «with» + «frase» es más corriente.]
4b) (C. no E.) The house, whose windows were all broken, was a depressing sight; The car, whose handbrake wasn’t very reliable, began to slide backwards.
[Los pronombres relativos posesivos con antecedente «cosa» en cláusulas no especificativas son «whose» y «of which.» «whose» se emplea tanto para animales como para cosas. «of which» es posible usarlo para cosas, pero es poco corriente excepto en Inglés muy formal.]
5. the year when ( = in which) he was born; the day when ( = on which) they arrived. The hotel where ( = in/at which they were staying. The reason why he refused is …
[«when,» «where» y «why» son adverbios relativos. «when» puede sustituir a «in/on which» (referido al tiempo). «where» puede sustituir a «in/at which» (referido al espacio). «why» puede sustituir a «for which» («The reason why he refused is …»). «when,» «where» y «why» usados de esta forma son llamados «adverbios relativos.»]
A Practical English Grammar (A.J. Thomson & A.V. Martinet) 