当DNA分子的一条单链中=0.7时，在整个DNA分子中这种比例是（　　）

When are you going?

默写。

   The first telephone cards, produced in 1976, were Italian. Five years later the first British card appeared, and now you can buy cards in more than a hundred countries. People usually start collecting cards because they are small and light and you do not need much space for them. It is also a cheap hobby for beginners, although for some people it becomes a serious business. In Paris, for example, there is a market where you can only buy telephone cards, and some cards cost up to ￡4,000.The first Japanese card has a value of about ￡28,000. Most people only see cards with prices like these in their collectors' magazine.

硫酸铵在强热时分解的产物是二氧化硫、氮气、氨气、水，则该反应化合价变化和未变化的氮原子数之比为