Introductory Word.—The substantive clause may be introduced by—
1. The relative pronouns, what, whatever, whatsoever, who, whoever, whoso, whosoever, which, whichever. When introducing noun clauses none of these words have an antecedent, hence it might be more precise to call them merely pronouns. Their office is more than an introductory one, for they have a function within the noun clause, just as relative pronouns have within adjective clauses.—“I wondered who the priest was that wore it.”—Howells. Here the pronoun who is the subjective complement of the verb was in the clause.
2. The adjectives what, whatever, whatsoever, which, whichever, whichsoever. These are indefinite limiting adjectives.—Tell me what time it is.
3. The words if, that, whether. These are ordinarily subordinating conjunctions, but when introducing noun clauses they should not be considered connectives at all; for a subject does not need to be connected to its predicate, nor a complement to the verb it completes, nor an appositive to the noun it explains. These introductory words serve rather to put the clause into shape, to make it appear as a subordinate part of the sentence.—“‘I wonder if his heart is any softer,’ thought the Fox.”—Froude. “The truth now flashed upon me that my companion was a schoolmaster.”—Lamb.
The introductory that is sometimes understood.—“It is true all things have two faces, a light one and a dark.”—Carlyle.
Whether usually takes or as a correlative,—“Chaucer did not waste time in considering whether his age were good or bad.”—Lowell.
4. Conjunctive adverbs, like where, when, how, why. These words always modify some word in the clause.—“We need not say how much we admire his public conduct.”—Macaulay. How modifies the adverb much.
5. But or but that, being equivalent to that not.—“‘Who knows but in the end I may turn into a dog?’ said the Fox.”—Froude.
“There” used as an Anticipative Subject.—We have already spoken of the anticipative subject it, whose office is to throw the real subject after the predicate verb. Another word used in the same way is there; for example, “There is no good reason for a bad action.”—Spurgeon.
This word is not the adverb there, for it conveys no idea whatever. It does nothing at all for the meaning of the sentence, as is shown by our slighting it in reading.