可用5%NaHC03水溶液萃取的是()
A.5,4-_甲基黄铜
B.5,3-二甲基黄酮
C.5,4.二甲氧基黄酮
D.7,4-_羟基黄酮
E.7,4-=甲氧基黄酮
参考答案:D
There _______ a football match tonight. [ ]
A. were
B. are
C. was
D. will be
地下水资源的组成及其之间的关系如何?