OG11-21

21.   Paleontologists believe that fragments of a primate jawbone unearthed in Burma and estimated at 40 to 44 million years old provide evidence of a crucial step along the evolutionary path that led to human beings.

(A) at 40 to 44 million years old provide evidence of

(B) as being 40 to 44 million years old provides evidence of

(C) that it is 40 to 44 million years old provides evidence of what was

(D) to be 40 to 44 million years old provide evidence of

(E) as 40 to 44 million years old provides evidence of what was

Idiom + Agreement

The verb estimated must be followed by the infinitive to be, not the preposition at. The fragments were estimated to be a certain age. The plural subject fragments requires the plural verb provide.

A     Estimated is incorrectly followed by at

B      Estimated should be followed by to be, not as being, the singular verb provides incorrectly follows the plural subject fragments

C     Introducing a clause, that it is ..., creates an ungrammatical sentence; the singular verb provides does not agree with the plural subject fragments

D     Correct. In this sentence, the verb estimated is correctly followed by the infinitive to be.

E      Estimated is incorrectly followed by as, the singular verb provides does not match the plural subject fragments

The correct answer is D.

选项C中的意思是说estimate后面不能加that呢，还是说这个从句改写成that they are 40 to 44 million years old就不是ungrammatical sentence了？对个ungrammatical的说法很困惑。。。

刚总结到OG11-27题，estimate后面可以加that

27.   Health officials estimate that 35 million Africans are in danger of contracting trypanosomiasis, or “African sleeping sickness,” a parasitic disease spread by the bites of tsetse flies.