什么叫湿空气的焓？
参考答案：
湿空气是由干空气和水蒸汽组成。湿空气的焓即湿空气所含的全热量，用符号i表示。全热量为潜热和显热的总和。
你一定有过很多难忘的假期，它们给你留下了许多美好的回忆。请你描述你印象最深刻的那个假期。（不少于60字）
1.Where did you...? 2. What did you do? 3. How was the weather there?
4. How were the people and the food there? 5. What did you think of it?
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信用证支付方式中，开证申请人与开证行之间存在着一种（）
A.以信用证为内容的合同关系
B.委托关系
C.担保关系
D.委托代理关系
