Their actions （ ）the stability and security of the region.
A、harden
B、frighten
C、brighten
D、threaten
【正确答案】：D
【题目解析】：句意：他们的行为对这一地区的稳定和安全造成威胁。harden v. 变硬，变严厉 He hardened his voice. frighten v. 使惊恐 She doesn’t frighten easily.brighten v. 使更明亮 brighten up 增添乐趣 A letter will usually brighten up a person’s day. 使人一天心情愉快。threaten v. 威胁 The attacker threatened them with a gun.
