光纤通信系统的不中断业务监测常在（）中使用。
A、系统调测
B、故障检查
C、日常维护
参考答案：C
Tom has been absent for two days．Do you know what _________ to him?
A．has happened
B．would happen
C．was happened
D．had happened
风湿性关节炎关节痛特点不正确的是
A．以膝、踝、肩、髋关节多见
B．病变关节红肿热痛，呈游走性
C．起病急剧
D．以链球菌感染为主
E．可有关节僵直和畸形改变
