重点讲解：
1. the center of
中心；中央；中部；
eg. A large wooden table dominates the centre of the room.
一张大木桌摆在房间正中央Q!_)s79KI0Su8l。
eg. Buses go to and from between the center of the city and the city limits.
公共汽车往返行驶于市中心和城市边缘之间q9;M,+JoRX@k2QuURl&E。
2. built-up
建筑物密集的；
eg. A speed limit of 30 mph was introduced in built-up areas.
在建筑密集区域，车速限制为每小时30英里F!uiRhgbF#n。
eg. The little field was surrounded by the university of maryland and a heavily built-up area.
这个小小的机场处在马里兰大学和一片稠密建筑物的包围之中TMi~SC-8_FD;EFKk。
eg. The land to the west is nearly all built-up.
西面的土地几乎全都已建筑饱和l4fNAvVbNGBtP+i^@。