The _______ income of the common people has been greatly increased in the past thirty years ______ the reform and opening-up policy in China.

The annual Energy & Environment Conference calls on our human beings to _______environmental issues.

Since nobody is here, the meeting will be delayed until tomorrow. The underlined word means ___.

Is that the reason ________he explained to all at the meeting for his carelessness in his work?  Actually we think he is a man who is hard ________ himself especially in work. 

 All the classes in this school _________ 60 students though they are of different ages。