As a developing country, we must keep（）with the rapid development of the world economy.

单项选择题The police let him go, because they didn’t find him guilty （）the murder.

A. of
B. in
C. over
D. on

单项选择题The fact that the management is trying to reach agreement （）five separate unions has led to long negotiations.

A. over
B. in
C. upon
D. with