I didn’t know          at first, but later we became good friends.

A．who is the boy

B．who the boy is

C．who was the boy

D．who the boy was

建筑安装企业工程价款结算，凡属工程质量问题，所发生的返工、返修等费用记入 ( )。

A．成本费用

B．营业外支出

C．其他应付款

D．销售折扣