Thanks to the joint efforts made by the leaders of China and the US over recent years, mutually Sino-US relations have made remarkable progress.
A. adaptable
B. beneficial
C. relevant
D. convenient
网友回答
A. adaptable
(答案→)B. beneficial
C. relevant
D. convenient
解析：
B 句意：由于近年来中美两国领导人的共同努力，双边互惠的中美关系取得了长足的发展。beneficial意为“有益的”，符合句意。adaptable有适应能力的；relevant相关的；convenient方便的。