问题
选择题
__________ I admit that the problems are difficult, I don’t agree that they cannot be solved.
A.When
B.While
C.As
D.Since
答案
答案:B
__________ I admit that the problems are difficult, I don’t agree that they cannot be solved.
A.When
B.While
C.As
D.Since
答案:B
关于物质分类的正确组合是
分类 组合 | 碱 | 酸 | 盐 | 碱性氧化物 | 酸性氧化物 |
A | Na2CO3 | H2SO4 | NaHCO3 | SiO2 | CO2 |
B | NaOH | HCl | NaCl | Na2O | CO |
C | NaOH | CH3COOH | MgCl2 | Na2O2 | SO2 |
D | KOH | HNO3 | CaCO3 | CaO | SO3 |