现有如下三个热化学方程式：
（1）H2(g)+O2(g)===H2O(g)，△H＝a kJ·mol-1
（2）H2(g)+O2(g)===H2O(l)，△H＝b kJ·mol-1
（3）2H2(g)+ O2(g)===2H2O(l)，△H＝c kJ·mol-1
下列关于它们的表述正确的是[ ]
A．它们都是吸热反应
B．a．b．c均为正值
C．a＝b
D．2b＝c
答案：D
综合填空：根据短文大意选择方框内的单词，并用其正确的形式填入空白处，使补全后的短文意思通顺，语法正确，结构完整。（5分）
小题1: Sunday, Tom goes out for a picnic with his friends. They take some 小题2: with them. Jane wants Tom to sing some songs with him, but he has 小题3: time. He has to 小题4: . Jim and Maria would like to help Tom. Michael gets some water for them. And Steve 小题5: a kite with the dog. They are all very happy. |