题目

 Linda won’t watch TV unless she her homework in time. A. finishes                     B. finish C. finishing                    D. to finish 答案：选A。考查时间状语从句的用法。时间状语从句中, 如果主句用一般将来时, 从句要用一般现在时。复数z=a（a-1）+ai为纯虚数，则实数a的值为（　　）A．0B．1C．0或1D．1或2