未知题型 In the passage, 'screening' (Line 1, Para. 3) refers to______.A．testing employees for illnessB．revealing something that hidesC．checking on potential employeesD．conducting online researches

未知题型 Social networks websites are used by many employers because the former______.A．help reveal what kind of person an job candidate isB．can spread the information of the company in a fast wayC．save companies lots of money on communicationD．help improve employer-employee relationship

单项选择题 光监测信道(OSC)的光功率是（ ）的测试项目。A. SDH传输设备B. 波分复用传输设备###SXB##