单项选择题
A.option
B.duty
C.obligation
D.penalty
单项选择题 In the past ten years skyscrapers have developed ()in Chicago and New York City.
单项选择题 Satellite communications are so up-to-date that even when ()in the middle of the Pacific, businessmen can contact their offices as if they were next door.
单项选择题 If the world is to remain peaceful the utmost effort must be made by nations to limit local ()