The customs duties act( )an essential leverage on regulating import and export behavior.
A. at B. as C. in D. to
The main reason why people fail to act when they stay together is that______.
A) they are afraid of emergencies
B) they are reluctant to get themselves involved
C) others will act if they themselves hesitate
D) they do not feel any direct responsibility for those who need help
As the chairman is ill, I am asking Mr. Sharp to act ______ him.
A.on
B.as
C.for
D.up
According the theory of kin selection, humans tend to act altruistically
A.for the sake of desired reproduction.
B.out of self-interest.
C.on the request of natural selection.
D.because of kind nature.