问题补充：
What will we do when all the oil in the world has ?
A. run out of
B. been given out
C. been used up
D. given off
答案：
A. run out of
B. been given out
(答案→)C. been used up
D. given off
解析：考查词组：ABC都有“用完”的意思，run out of是及物动词短语，应该是被动语态，give out 跟run out 一样，无被动。Use up用被动形式， been used up， give off是散发，选C。
