根据句意和首字母写出相应的单词。

1. Our teacher always e_______ us to work hard at English and do more for people in the future.

2. S_______, when he went into the dark hole for the first time alone, he didn't come up any more.

3. If you go out in summer, you'd better wear sunglasses to p_______ your eyes from strong sunlight.

4. Giant pandas are in danger now, they are e_______ animals.

5. Every year a lot of t_______ come to visit the Palace Museum to see those things used in the past.

已知H₂O(g)H₂O(l) ΔH=Q₁ kJ·mol^-1

C₂H₅OH(g) C₂H₅OH(l) ΔH=Q₂ kJ·mol^-1

C₂H₅OH(g)+3O₂(g)2CO₂(g)+3H₂O(g) ΔH=Q₃ kJ·mol^-1

若使23 g液体酒精完全燃烧，最后恢复到室温，则放出的热量为__________kJ（   ）

A．Q₁+Q₂+Q₃

B．0.5(Q₁+Q₂+Q₃)

C．0.5Q₁-1.5Q₂+0.5Q₃

D．1.5Q₁-0.5Q₂+0.5Q₃