根据句意和汉语提示，填写单词。

1. His brother is a _________(军人). He joined the army five years ago.

2. We must _________(面对) these problems and find ways to get over them.

3. The old man _________(将……视为) the poor boy as his own son.

4. ________ (除非) we work hard, we will hardly ever learn English well.

5. There is a popular saying in sports meeting, "________(友谊) first, competition second."

下列各组中的两个反应，前一个反应放出的热量比后一个反应放出的热量多的是（反应物参与反应的物质的量均按化学方程中的化学计量数计算） [ ]

①2H₂(g)+O₂(g) = 2H₂O(g)

2H₂(g)+O₂(g) = 2H₂O(l)

②C(s)+O₂(g) = CO₂(g)

C(s)+1/2O₂(g) = CO(g)

A．只有①

B．只有②

C．①②

D．①②都不符合题意