展车前排车窗，左右对应车窗玻璃升降的高度（） A.左高右低 B.右高左低 C.保持一

图为动植物细胞的结构模式图，请据图回答下列问题：

（1）图2是______细胞，因为细胞中有[______]______、[______]______和[______]______．

（2）具有保护和支持细胞功能的是[______]______．

（3）犹如细胞的门户，凡是进出细胞的物质都要由此构造进行选择的是[______]______．

（4）枫树的叶子秋天会变成红色，是因为在枫叶中叶肉细胞的[______]______中溶解有花青素．

（5）含有遗传物质的是[______]______．

（6）图2中的能量转换器是[______]______和[______]______．

在数据流程图中，一般把信息流分为两种：变换流和（）

(B)

You can tell the age of a tree by counting its ring. But these records of a tree’s life really say a lot more. Scientists are using tree ring to learn what’s been happening on the sun’s surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk, taking up chemical elements from the air. By looking at elements in the rings from a certain years, scientists can tell what elements were in the air that year. Dr. Stevenson is analyzing one element, carbon-14, in ring from both living and dead tree. Some ring go back almost ten thousand year to the end of the Ice Age. When Stevenson followed the carbon-14 levels changed with the intensity of solar burning. You see, the sun has cycles. Sometimes it bums fiercely, and at other times it is relatively calm. During the sun’s violent periods, it throw off charged particles in fast moving streams called "solar winds". The particularly interfere with the formation of carbon-14 on earth. When there is more solar wind activity, less carbon-14 is produced. Ten thousand years of tree ring show that the carbon-14 level rises and falls about every 420 years. The scientists concluded that solar wind activity must follow the same cycle.

The purpose of the scientists in studying tree ring is to（）

A. examine the chemical elements in Ice Age

B. look into the pattern of solar wind activity

C. analyze the composition of different trees

D. find out the origin of carbon-14 on earth

电缆接线盒按电压等级分（）。

A、1140伏

B、64伏

C、104伏

D、354伏

在客户服务中心现场管理种质量主办在客户服务过程中的作用是（）和统计预测者。