改错题 16.The personal income tax did not become permanent in the United States until the First World War; before that time the federal government was dependent on tariffs to be their main source of revenue.

A、 the federal government was dependent on tariffs to be their main source of revenue
B、 the federal government had depended on tariffs as its main source of revenue
C、 tariffs were what the federal government was dependent on to be its main source of revenue
D、 the main source of revenue for the federal government was dependent on tariffs
E、 for their main source of revenue, tariffs were depended on by the federal government

【正确答案】 B

【答案解析】Agreement; Logical predication
The First World War is designated as past tense in the opening clause of this sentence. The relationship between that time and whatever happened earlier can be most clearly indicated by using the past-perfect tense for the earlier events.
[T]he federal government is a singular subject of the second clause, so a singular pronoun, its rather than their, must refer to it. The phrase was dependent on causes unnecessary wordiness, as does the passive construction in E.
A The plural pronoun their inappropriately refers to the singular noun government.
B Correct. The pronoun its agrees with the singular subject government, and the past perfect, active verb had depended refers clearly to government activity prior to the First World War.
C This version of the sentence is wordy because of the inverted word order that makes the subject of the second clause an object of the preposition on.
D This version of the sentence nonsensically makes source the subject of the verb was [dependent on].
E The plural possessive pronoun their does not agree with its singular antecedent government. In fact, because of the placement of tariffs immediately after the opening prepositional phrase, their seems at first to refer to tariffs, which is illogical. The passive verb form were depended on is wordy and indirect.
The correct answer is B.