As ___ matter of fact, he has been out o

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问题选择题

As ___ matter of fact, he has been out of ___ work for three months.

A. the; /
B. a; /
C. the; the
D. a; the

答案

答案：B

选择题

已知H—H键键能(断裂时吸收或生成时释放的能量)为436 kJ·mol^－1，N—H键键能为391 kJ·mol^－1，根据热化学方程式：N₂(g)＋3H₂(g)===2NH₃(g)　ΔH＝－92.4 kJ·mol^－1。则N≡N键的键能是

A．431 kJ·mol^－1

B．945.6 kJ·mol^－1

C．649 kJ·mol^－1

D．896 kJ·mol^－1

判断题

市场营销组合是一个单一结构。