built-up

built-up 的音标为 [bɪlt juːp]，基本翻译为“组合物；聚合体；填隙物；积累；增加；增补”。

速记技巧：可以将单词拆分为“built”（建造）和“up”（向上）两部分，帮助记忆。

"Built-up"这个词源于英语单词"built"和"up"，意思是"聚集的，密集的"。它的变化形式包括"built-up"（形容词形式）和"built-up area"（名词形式）。

相关单词：

"Build"：这个词直接来自于动词"build"，意思是建造，组装。它的变化形式包括"built"，"building"，"builder"等。

"Concentration"：这个词来源于拉丁语，意思是集中，聚集。它的变化形式包括"concentrated"，"concentration area"等。

"Dense"：这个词来源于拉丁语，意思是密集的，浓厚的。它的变化形式包括"densely"，"dense population"，"dense vegetation"等。

"Agglomeration"：这个词来源于拉丁语和法语，意思是聚集，凝结。它的变化形式包括"agglomerated"，"agglomeration area"，"agglomeration zone"等。

"Mega-city"：这个词来源于希腊语，意思是大型城市，特大城市。它的变化形式包括"mega-urban"，"megacity"，"megacities"等。

以上这些单词都与“built-up”有着密切的联系，它们都表示聚集、密集、大规模的意思。这些单词在英语中经常被用来描述城市、人口密集地区、大规模的聚集等概念。同时，这些单词也反映了人类社会的发展和城市化进程。

常用短语：

1. built-up area 人口稠密地区

2. built-up zone 建成区

3. a city with a built-up area of 5 million square kilometers 面积达5万平方公里的城市

4. built-up ratio 建成比例

5. built-up rate 建成率

6. built-up area growth rate 建成区面积增长率

7. built-up ratio of urban areas 城市建成比例

例句：

1. The city center is a bustling built-up area with shops, restaurants, and offices.

2. The built-up zone has expanded significantly in recent years, with new housing and commercial developments.

3. The built-up ratio of our city has increased steadily over the past decade.

4. The built-up rate of our city has exceeded that of many other cities in the region.

5. The built-up area growth rate of our city has remained steady over the past few years.

6. The urban areas in our country have a high built-up ratio, indicating that they are well developed.

7. The city is surrounded by a large built-up area, with many tall buildings and busy streets.

英文小作文：

Title: The Changing City - The Impact of Urban Expansion

Urban expansion has been a constant process in modern society, with cities constantly growing and changing shape. As the population continues to grow and urban areas expand, the built-up area of cities also increases, leading to changes in the urban landscape and the way people live their lives.

The built-up area of a city is not just about the number of buildings and roads, but also about the way these elements interact with each other and with the surrounding environment. As the urban area expands, new neighborhoods are created, leading to changes in the way people live and work, as well as changes in the economy and culture of the city.

However, urban expansion also brings challenges, such as traffic congestion, environmental pollution, and social issues like housing and inequality. Therefore, it is important for cities to plan their expansion carefully, balancing the needs of the present and future generations, while ensuring that the urban environment remains sustainable and livable.