They are living with their parents for the moment because their own house ________.
A. is being rebuilt B. has been rebuilt
C. is rebuilt D. has rebuilt
知识点：英语
A
句意：他们现在暂时和父母一起居住，因为他们自己的房子正在重建。根据句意可知，应使用现在进行时，且house与动词rebuild之间为被动关系，故使用现在进行时态的被动语态。
— Can I call you back at two o'clock this afternoon?
— I'm sorry, but by then I ________ to Beijing. How about five?
A. fly B. will fly
C. will be flying D. am flying
知识点：英语
C
根据问句中的two o'clock this afternoon和应答句中的by then可知所填词表示的动作在当时正在进行，用将来进行时，选C项。
The manager ________ the workers how to improve the program since 9 a．m.
A. has told B. is telling
C. has been telling D. will have told
知识点：英语
C
现在完成进行时表示：过去某一动作从过去开始一直延续到现在，现在刚刚结束或还在进行。句意：经理从早上9点开始就一直在不停的告诉工人们如何改进这个项目。根据句意选C项。
The manager was concerned to hear that two of his trusted workers ________.
A. will leave B. are leaving
C. have left D. were leaving
知识点：英语
D
此处用过去进行时表示过去将来时。这里were leaving表示“过去要离开”。句意：听到自己最信任的两个职员要离去，经理很担忧。