名词 “vacancy”
 单数vacancy,复数vacancies或不可数
- 职位空缺The company posted several vacancies for experienced engineers in its new research center. 
- 空房During the holiday season, it's difficult to find a hotel with any vacancies. 
- 空地They decided to plant a garden in the vacancy left by the old house. 
- 茫然She stared out the window with vacancy that suggested her mind was elsewhere. 
- 空位(固体中原子缺失的地方)Scientists are studying how vacancies in the crystal lattice affect the material's properties.