我想知道以下生字的英文解釋...請進入(急)10分!!!!

1)人口普查
2)自然的增加- -
3)網狀系統遷徙- -
4)出生比率
5)死亡比率
6)人口密度
7)土地面積
8)政府方針- -
9)人口金字塔- -?
10)年齡結構- -?
11)性別結構- -?
12)新到達- -?

Census - counting of populations in large scale in set interval
By-census - a census which takes place in between two censuses. The by-census is not as large scale as Census.
Net Migration - is the difference of immigrants and emigrants of an area in a period of time
Birth Rate - number of children born per year
Population Density - is the number of people per unit of area
Land Area - the size of a land surface
Government Policy - plans or actions adopted by the Government
Population Pyramid - a graphical illustration that shows the distribution of various age groups in a population which forms the shape of a pyramid

2007-11-07 23:45:41 補充：
Age Structure - the distribution pattern of age groupsSex Structure - the distribution pattern of sex groupsNew Arrivals - recently born babies