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