题目

Class is beginning. Will you please get the blackboard ________. A．to clean  B．cleaning    C．cleaned     D．having cleaned 答案：Ｃ15．计算（-1）×（-5）×（-$\frac{1}{5}$）的结果是（　　）A．-1B．1C．-$\frac{1}{25}$D．-25