UNIT  41. His employers could not complain about his work because  he was ______ in the performance of his duties.     A. derelict   B. penetrating   C. diversified   D. assiduous. employer  雇主，老板employee  雇员 assiduous  勤奋的insidious  阴险的，狡诈的 derelict  遗弃物relics  遗骨relict  残余物 penetrate  穿透permeate  渗透diffuse  弥漫diversify  使不同