Bunuel
Although World War II ended nearly a half century ago, Russia and Japan still have not signed a formal peace treaty; and both countries have been reticent to develop closer relations.
(A) have not signed a formal peace treaty; and both countries have been
(B) did not signed a formal peace treaty; and both countries have been
(C) have not signed a formal peace treaty; and both countries being
(D) have not signed a formal peace treaty; and both countries are
(E) are not signing a formal peace treaty; and both countries have been
OFFICIAL EXPLANATION
The sentence is grammatical as written. The present perfect verb
have … signed correctly indicates that they have not signed a peace treaty and are not on the verge of signing one. Further, the present perfect verb
have been correctly indicates that in the past both countries have been reluctant to develop closer relations and are still reluctant.
The answer is (A).In choice (B), the simple past
did does not capture the fact that they did not sign a peace treaty immediately after the war and still have not signed one.
Choice (C) is very awkward, and the present progressive
being does not capture the fact that the countries have been reluctant to thaw relations since after the war up through the present.
In choice (D), the present tense
are leaves open the possibility that in the past the countries may have desired closer relations but now no longer do.
In choice (E), the present progressive tense
are … signing, as in choice (D), leaves open the possibility that in the past the countries may have desired closer relations but now no longer do.