阻值不随外加电压或流过的电流而改变的电阻叫线性电阻。（）
参考答案：对
元朝时期，哪些地方受中央直接管理？
①河北 ②河南 ③山西 ④山东
A．①②③
B．②③④
C．①②④
D．①③④
He said he was very busy, but ______ he had nothing to do. [ ]
A. at last
B. as a result
C. in a word
D. in reality
