*Exceptions:*—
(a) When the antecedent is defined, e.g. by a possessive case, modern English uses who instead of that. It is rare, though it would be useful,[7] to say "His English friends that had not seen him" for "the English friends, or those of his English friends, that had not seen him."
(b) That sounds ill when separated from its verb and from its antecedents, and emphasized by isolation: "There are many persons that, though unscrupulous, are commonly good-tempered, and that, if not strongly incited by self-interest, are ready for the most part to think of the interest of their neighbours." Shakespeare frequently uses who after that when the relative is repeated. See "Shakespearian Grammar," par. 260.
(c) If the antecedent is qualified by that, the relative must not be that. Besides other considerations, the repetition is disagreeable. Addison ridicules such language as "That remark that I made yesterday is not that that I said that I regretted that I had made."
(d) That cannot be preceded by a preposition, and hence throws the preposition to the end. "This is the rule that I adhere to." This is perfectly good English, though sometimes unnecessarily avoided. But, with some prepositions, the construction is harsh and objectionable, e.g. "This is the mark that I jumped beyond," "Such were the prejudices that he rose above." The reason is that some of these disyllabic prepositions are used as adverbs, and, when separated from their nouns, give one the impression that they are used as adverbs.
(e) After pronominal adjectives used for personal pronouns, modern English prefers who. "There are many, others, several, those, who can testify &c."
(f) After that used as a conjunction there is sometimes a dislike to use that as a relative. See (c).
*9. Do not use redundant "and" before "which."[8]*
"I gave him a very interesting book for a present, and which cost me five shillings."
In short sentences the absurdity is evident, but in long sentences it is less evident, and very common.