问题
问答题 简答题
什么简约信息位点Pi？
答案
参考答案：
指基于DNA或蛋白质序列，应用最大简约法构建系统发育树时，如果某个位点的状态存在两种或两种以上，每种状态出现两次或两次以上，这样的位点称简约信息位点。
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什么简约信息位点Pi？
参考答案：
指基于DNA或蛋白质序列，应用最大简约法构建系统发育树时，如果某个位点的状态存在两种或两种以上，每种状态出现两次或两次以上，这样的位点称简约信息位点。
| 阅读理解。 |
| Have you ever (曾经) seen snow? A lot of people in the world have not. A lot of countries never have snow. In the north of England, there is quite a lot of snow every winter, but in the south of England, there is usually little snow. When a student from a warm country comes to England in the autumn for the first time, he feels cold at first. There are often dark clouds, grey skies and cold rain in England in autumn, and most students from warm countries do not like this kind of weather. But snow is different. It is very cold, but it is very beautiful. After a few dark mornings, the student wakes up one day and there is a lot of light in his room. He thinks, "It must be late," and gets up quickly. But no, it is not late at all. He looks out of the window and there is snow everywhere. The light in the room comes from that clean, beautiful white snow. |
| 1. Many people ______. |
[ ] |
| A. have ever seen snow B. have never (从来没有) seen snow C. often see snow D. see snow once a year |
| 2. There is usually ______ snow in the south of England. |
[ ] |
| A. a little B. much C. a few D. little |
| 3. When a student from a ______ country comes to England in the autumn, he feels ______ at first. |
[ ] |
| A. hot; cold B. warm; cold C. warm; hot D. hot; warm |
| 4. Most students from warm countries ______. |
[ ] |
| A. like the weather in England B. don't like the weather in England C. don't like snow D. often see snow in their countries |
| 5. There is a lot of light in the room because ______. |
[ ] |
| A. there is a lamp (灯) B. it is daytime C. it is fine D. there is snow outside |