The government called out policemen to suppress the riot.
A
tosuppresstheriot在句子中是作目的状语，表示“警察来是镇压动乱的”，所以答案为A。
By the middle of the 21st century, the vast majority of the world ’s population will be living in cities _______ in the country.
Thepolicemancameuptothelonelyhousewiththedoor_______,_______thereforawhileandthenenteredit.
China is a mountainous country.Hills,mountains,and plateaus cover _______ of the total area.
Thevisitingministerexpressedhissatisfactionwiththetalks,________thathehadenjoyedhisstayhere.
Thisis________goodreadinghabitsarenotonlyanimportantstudyskillforthestudent,butalsoanimportantlifeskillforanyone.