钉书机用钢铁制成条的钉书钉
参考答案：83052000
-- Why do you look so worried?
-- My computer broke down and my essay _____ since.
A．has been left unfinished
B．has left to finish
C．was left to finish
D．had been left unfinished
柴油机发动机喷油器试验器用油应为沉淀后的（）
A、0号轻柴油
B、煤油
C、液压油
D、机械油
