W-CDMA系统采用的多址方式为（）A.FDMA B.CDMA C.TDMA D.F

煤矿安全生产的主要规程是指（）

A、爆破作业规程

B、煤矿安全规程

C、作业规程

D、操作规程

E、煤矿救护规程

Matter
Look at all the things around us: chairs, desks, cupboards, papers and pens in our classroom; motor cars, bicycles and buses in the streets; trees, plants and animals in the countryside; birds, aeroplanes and clouds in the sky; fishes, seaweeds and corals in the sea; stars, the moon and the sun in outer space. These and all other things including the human body, are examples of matter. Matter is anything that takes up space and has weight.
What Is Matter Made of
Since ancient times, learned men or philosophers have thought about matter and what it is made up of. One group of philosophers thought that matter was made .up of a substance called "hyle" (实质). Another group of philosophers said that matter was made up of four substances, namely earth, water, air and fire. A third group believed that matter was made up of very tiny particles which were too small to be seen. These particles were so small that they could never be further divided into smaller particles. They gave the particles the name atoms which means "those which cannot be divided". The difference between the various kinds of atoms and the ways in which they were joined were supposed to result in the different kinds of matter.
All these ideas arose purely from the mind and were not based on investigation. For many years, people believed in the second idea. But actually it is the third idea that is nearer to our present concept of matter.
Dalton’s Atomic Theory
In the early nineteenth century, Dalton, an English school teacher, stated in this atomic theory that matter was made up of tiny, indivisible particles, which he also called atoms. His laboratory work showed him that atoms could neither be divided into smaller parts nor could they be destroyed. He pictured matter as being made up of tiny solid spherical atoms. Today the idea of the atoms has been accepted. But further work has shown that contrary to Dalton’s findings, atoms are made up of even smaller particles.

活络管子板牙由（）为一组，用来套管子（）螺纹。

下列行标说法正确的是（）。

A.能够在单元格快捷菜单里设置列宽

B.可以在公式选项卡里打开系统附件计算器

C.可以在行标上右击清除整行的内容

D.可以自定义列标表名称

假设一棵二叉树的后序遍历序列为DGJHEBIFCA，中序遍历序列为DBGEHJACIF，则其前序遍历序列为 【2】 。