时是不及物动词，没有被动形式；其次，句中的already 表示完成概念。因此选择表示主动兼完成的to have left。

答案：A

26. I'm moving to the countryside because the air there is much fresher than________ in the city.

A. ones B. one C. that D. those

解析：检查考生对代词的掌握和运用能力。空格里所填的此用来指代不可数名词air，所以用that。

答案：C

27. ________ in the mountains for a week, the two students were finally saved by the local police

A. Having lost B. Lost C. Being lost D. Losing 解析：检查考生对非谓语动词的掌握和运用能力。首先，表示“失踪”用be lost；其次，语境中for a week，表示完成概念，所以用过去分词。

答案：B

28. David has won the first prize in singing; he is still very excited now and feels________ desire to go to bed.

A. the most B. more C. worse D. the least

解析：检查考生在特定语境下对名词修饰语的辨析和运用能力。上文中的excited 是信息词，由于兴奋而没有睡觉的欲望。

答案：D

29.They _______ on the program for almost one week before I joined them, and now we ________ it as no good results have come out so far.

A. had been working; are still working B. had worked; were still working

C. have been working; have worked D. have worked; are still working 解析：检查考生对动词时态的掌握和运用能力。第一空，时间状语从句before I joined them决定了要使用响应的过去时态；第二空，now 决定了要使用现在时态。

答案：A

30. In our childhood, we were often _______ by Grandma to pay attention to our table manners.