----- Tom has won the first prize in the singing contest of our school.

------- __________ .You see he always works hardest.

A．He is a lucky dog

B．No pains , no gains

C．All roads lead to Rome

D．It is no use reasoning with a fool.

某大型机械原值25元，折旧年限规定为8年，预计月平均工作210小时，预计净残值率3％，该机械某月实际工作270小时，则用工作量法计算的该月折旧额为（）元。

A.2400

B.2880

C.3000

D.3248