vacant  
adjective uk/ˈveɪ.kənt/ us/ˈveɪ.kənt/
  (EMPTY)         
 B2 空的;未被占用的
not filled or occupied; available to be used
  The hospital has no vacant beds. 这家医院没有空床位。 
 Compare: engaged (IN USE)
 B2 (工作职位)空缺的
A vacant job is one that no one is doing and is therefore available for someone new to do
  The position fell (= became) vacant when Rodman was promoted. 罗德曼提升之后这个职位就空缺了。 
   (NOT RESPONDING)      
 无聊的;茫然的;没精打采的
showing no interest or mental activity
  She had a vacant look/expression on her face. 她一脸的茫然。