Is Chen Jie in the bedroom? _______
A:Yes, it isn't.
B:No, it's in the kitchen
C:Yes, she is.
用化学用语填空:(1)三个氢原子____
(2)两个五氧化二氮分子____(3)3个氢氧根离子____
(4)氧化镁中镁元素为+2价____