下列化合物中,氯元素的化合价最高的是( )
A.ClO2
B.NH4ClO4
C.KClO3
D.NaClO
答案:B
It is reported that ______ number of college students ______ growing year by year.
A.a; are
B.the; is
C.the; are
D.a; is
可燃性气体具有哪些特点?