yesterday       
 adverb uk/ˈjes.tə.deɪ/ us/ˈjes.tɚ.deɪ/
A1 昨天
on the day before today
  He called yesterday while you were out. 昨天你外出时他打电话来了。 
 I saw her yesterday afternoon. 我昨天下午见到她了。 
 - More examples
 - I rang them yesterday to check when they were arriving.
 - The police have deduced that he must have left his apartment yesterday evening.
 - The company's shares dived by 90p to 165p on the stock market yesterday.
 - The book was delivered yesterday with a note saying the bill for it would follow in a day or two.
 - Mr Gubbay said yesterday that he will not be reapplying for the job.
 
yesterday            
noun uk/ˈjes.tə.deɪ/ us/ˈjes.tɚ.deɪ/
 [ U ]昨天 
the day before today
  "Is that today's paper?" "No, it's yesterday's." “那是今天的报纸吗?”“不,是昨天的。” 
 the day before yesterday 前天
two days ago
  I called her the day before yesterday. 我前天给她打了电话。 
  [ C or U ]近日,日前;往昔 
the recent past
  Nobody's interested in yesterday's pop stars. 没人对过气明星感兴趣。 
 These songs are a part of all our yesterdays. 这些歌曲是我们所有往事的一部分。