---I have seen so little of Mike______. Is he away on business?---Oh, no. He just leaves for his office and returns very ______.

With the word “ PM2.5” _________ appearing in media reports, people pay greater attention to it and seek health tips for smoggy days.

Process so far has been very good．______，we are sure that the project will be completed on time．

He had planned to make a compromise，but        he changed his mind at the last minute．

It is the prevention of disease______its successful treatment that has led to the rapid increase of the world’s population.