单项选择题The spectrum of a sequence is , then X[3] in the 6-point DFT of this sequence is equal to A、2 3 B、1 3 C、3 2 D、3
问答题电动刮水器主要由直流电动机、[填空1]、自动停位器、刮水开关、联动机构及刮水片等组成。