问题补充：
The government is and will take the necessary steps to maintain security and stability.
A. on the alert
B. out of control
C. on guard
D. in vain
答案：
(答案→)A. on the alert
B. out of control
C. on guard
D. in vain
解析：on the alert (=alert; watchful; careful) 警惕，小心：Drivers must be on the alert for traffic signals. (=Drivers must be especially careful to see signals when driving a car.) (司机必须密切注视交通信号。)out of control 失去控制；on guard站岗；in vain 徒劳，无效。
