测定电解质的方法有()
A.化学法
B.原子吸收法
C.PCR法
D.火焰光度法
E.离子选择电极法
参考答案:A, B, D, E
已知全集U={1,2,3,4},集合M={1,4},N={1,2},则集合{2,3,4}=[ ]
A.CUM∪CUN
B.CUM∩CUN
C.M∪N
D.M∩N
Is this research centre _____ is full of modern equipment you always mention. [ ]
A. where
B. that
C. the one that
D. the one where