【题目】Citizens are _____ to exercise their rights, but under no circumstances can they violate other people’s rights.
A. on trackB. on schedule
C. at easeD. at liberty
在线课程【答案】D
【解析】
考查介词短语。句意：公民可以自由地行使自己的权利，但他们绝不能损害他人的权益。A. on track走上正轨；B. on schedule 按时；C. at ease安逸；舒适；D. at liberty自由地。故选D。