Can I sit here?—Sorry. It has been _____.[ ]

Mary hurt her friend’s feeling, but she didn’t do it ____purpose

Before the 2008 Olympic Games took place, _________ the young _________ the old took an active part in learning English in Beijing.

The fact that so many people still smoke in public place _______that we may need antionwide campaign to raise awareness of the riks of smoking

_________ the problem of land erosion getting more serious, the government is searching for a way to deal with it.