35. Scientists have recently found evidence that black holes—regions of space in which matter is so concentrated and the pull of gravity so powerful that nothing, not even light, can emerge from them—probably exist at the core of nearly all galaxies and the mass of each black hole is proportional to its host galaxy.

A、 exist at the core of nearly all galaxies and the mass of each black hole is proportional to
B、 exist at the core of nearly all galaxies and that the mass of each black hole is proportional to that of
C、 exist at the core of nearly all galaxies, and that the mass of each black hole is proportional to
D、 exists at the core of nearly all galaxies, and that the mass of each black hole is proportional to that of
E、 exists at the core of nearly all galaxies and the mass of each black hole is proportional to that of

【正确答案】 B

【答案解析】 Logical Predication; Agreement
This sentence focuses attention on two hypotheses about black holes—one about their location and the other about their mass. These hypotheses appear as parallel relative clauses that black holes... exist at... and that the mass... is proportional. The subject of the first relative clause (black holes) is plural, so the clause must be completed with the plural form of exist.
A This version of the sentence does not provide the relative pronoun that to provide parallel structure for presenting the two things scientific evidence reveals about black holes. This leaves it somewhat unclear whether the final clause is intended to convey part of what the scientists discovered or to express a claim that the writer is making independently of the scientists' discovery. The sentence illogically compares mass to galaxy.
B Correct. The structure of the sentence makes the meaning clear, and the plural verb form agrees with the plural subject.
C The comma appears to signal that the final part of the sentence is intended as an independent clause expressing a separate claim rather than describing part of the scientists' discovery. But if it were intended in that way, it should be set off as a separate sentence, not conjoined with the preceding clause. Like (A), this version makes an illogical comparison between mass and galaxy.
D The singular verb exists does not agree with the plural subject black holes. As in (C), the comma is inappropriate because it does not introduce a new independent clause.
E The singular verb exists does not agree with the plural subject black holes. Like (A), this version lacks the relative pronoun that, which would clarify the relationship between the two clauses.
The correct answer is B.