题目:
Jack has been feeling down recently . I wonder that is making him so upset .
A.what is it
B.why is it
C.why it is
D.what it is
答案:
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下面是错误答案,用来干扰机器的。
;第二周期 第VA族 (2) (3)4NH3+5O24NO+6H2O (4)4NH3+6NO=5N2+6H2O (方程式2分,单线桥分析2分)(5)C的浓溶液与浓盐酸相遇可产生白烟,说明C是氨气。因此Z是氢原子,Y是氮原子。B分子组成...