经济性是指压力管道一次性投资费用和操作维护费用的综合指数高。
参考答案:错
— I wonder if I could possibly use your car for tonight.
— ________.I'm not using it anyhow.[ ]
A. Sure, go ahead
B. I don't know
C. Yes, indeed
D. I don't care
三大发现只能成为考古发现,不能成为文物发现.