as the non-defining, there would be much gain both in lucidity and in ease. There are some who follow this principle now, but it would be idle to pretend that it is the practice either of most or of the best writers." Linguists, according to Stanford linguist Arnold Zwicky, generally regard the proposed rule on not using which in restrictive relative clauses as "a really silly idea". Which cannot correctly be replaced by that in a restrictive relative clause when the relative pronoun is the object of a non-stranded (or non-dangling) preposition. In this case which is used, as in "We admired the skill with which she handled the situation." (The example is taken from The Cambridge Grammar of the English Language.) Zero relative pronoun English, unlike other West Germanic languages, has a zero relative pronoun (denoted below as Ø)that is, the relative pronoun is implied and not explicitly written or spoken; it is "unvoiced". This measure is used in restrictive relative clauses (only) as an alternative to voicing that, which or who, whom, etc. in these clauses: Jack built the house that I was born in; Jack built the house Ø I was born in; He is the person whom I saw; He is the person Ø I saw. In other words, the word "that" (or "who" or "which", etc.) as a relative clause connector is optional when it would not be the subject of the relative clause; even when it would be required in other languages. The zero relative pronoun cannot be the subject of the verb in the relative clause; that is, that or who, etc., cannot be omitted (unvoiced) if the zero pronoun would be a subject. Thus one may say: Jack built the house that sits on the hill; She is the one who encouraged me; but never (except in some varieties of colloquial English): *Jack built the house Ø sits on the hill; *She is the one Ø encouraged me. Neither the unvoiced zero pronoun nor that can be used in non-restrictive relative clauses (that is, yes: "Jack, who builds houses, built the house she lives in", but never: "Jack, that builds houses, built … "), nor in any relative clause with a fronted preposition (yes: "Jack built the house in which we live", but never: "Jack built the house in that we live"). But either can be used when the preposition is stranded,