在锰酸钾(K2MnO4)中,锰元素的化合价是[ ]
A.+2
B.+4
C.+6
D.+7
答案:C
The education of _______young is always _______ hot and serious topic in modern society.
A.the; /
B.a; the
C./; the
D.the; a
Thanks your photo of your family. [ ]
A. to
B. at
C. for