Discretionary fiscal policy can be defined as:（）

A. a situation in which total government spending exceeds total government revenue during a specific time period, usually one year. 

B. a change in laws or appropriation levels that alters government revenues and/or expenditures. 

C. a situation in which total government spending is less than total government revenue during a time period, usually one year.

矿车整形前，若是人工整形，则手锤的（）禁止站人。

A.后方

B.前方

C.旁边