阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。
A skywell, or “tian jing” in Chinese, dating back to the Ming dynasty, is a typical feature of a traditional home in southern and eastern China. It 1 (design) to allow in light, improve ventilation (通风), and harvest rainwater. Less 2 (expose) to the outdoor environment, a skywell is smaller and distinct from a northern courtyard.
Despite the fact 3 a skywell’s size and design vary from region to region, it is almost always rectangular (长方形) and located in the core of a house. It is either enclosed by rooms on four sides 4 three sides plus a wall. When wind blows above a skywell house, it can enter the indoor space through the opening. Because outdoor air is often cooler, the incoming wind travels down the walls to the lower stories 5 creates airflow by replacing 6 (warm) indoor air, which rises and leaves through the opening.
Due to the 7 (revive) of traditional Chinese architecture, skywell buildings have been making a comeback. Architects are now looking towards the 8 (principle) behind skywells while designing new buildings 9 (save) energy. One example is the National Heavy Vehicle Engineering Technology Research Center in the eastern Chinese city of Jinan. A giant skywell is in the middle of the 18-storey glass-walled tower block, 10 (stretch) from the fifth to the top floor.
