对于炼焦制气厂水路来煤的贮煤场来说,其操作容量的设计一般按( )天的焦炉用煤量设计。
A.30~40 B.15~18 C.15~20 D.18~40
参考答案:C
—Do you want to see the film Pirates of the Caribbean 4 this evening?
—Pirates of the Caribbean 4? I _________ it before. Let me see, I _________ it 2 years ago.
A.saw; have seen
B.had seen; saw
C.have seen; saw
D.have seen; had seen
铁锈的主要成分是Fe2O3,除锈的原理是:Fe2O3 + 3H2SO4 = Fe2(SO4)3 + 3H2O。该原理利用的硫酸性质是
A.氧化性 B.还原性 C吸水性 D.酸性