请教NN有关宾语从句中时态问题

BlueBlue29

                                                                                                                                                有时候真的很困惑宾语从句里和主句谓语的时态问题。到底要不要一致呢？我看了有些题目主句谓语对从句的时态并没有什么影响，有些又是要考虑的。请问怎么破？在这先谢过各位了。
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[size=10.000000pt]OG18
[size=10.000000pt]The Organization of Petroleum Exporting Countries(OPEC) had long been expected to announce areduction in output to bolster sagging oil prices, butofficials of the organization just recently announcedthat the group will pare daily production by 1.5 millionbarrels by the beginning of next year, but only ifnon-OPEC nations, including Norway, Mexico, andRussia, were to trim output by a total of 500,000barrels a day.
[size=10.000000pt](A) year, but only if non-OPEC nations, includingNorway, Mexico, and Russia, were to trim output
[size=10.000000pt](B) year, but only if the output of non-OPEC nations,which includes Norway, Mexico, and Russia, istrimmed[size=10.000000pt](C) year only if the output of non-OPEC nations,including Norway, Mexico, and Russia, would betrimmed
[size=10.000000pt](D) year only if non-OPEC nations, which includesNorway, Mexico, and Russia, were trimmingoutput
[size=10.000000pt](E) year only if non-OPEC nations, including Norway,Mexico, and Russia, trim output
[size=10.000000pt] OA: E
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[size=10.000000pt]GWD （ChaseDream PREP2008语法笔记 Practice Test #2）
[size=10.000000pt]Trans World Entertainment Corporation, which owns the Record Town and Saturday Matinee retail chains,announced that since sales of up to one-fourth of its stores are poor, they will be closed。
A. that since sales of up to one-fourth of its stores are poor, they will be closed
B  it is closing up to one-fourth of its stores, which accounted for its poor sales
c. it was closing up to one fourth of its stores because of poor sales
d. to be closing, on account of poor sales, up to one-fourth of its stores
e having poor sales, such that up to one-fourth of its stores will be closed
OA: C



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