Online shopping is increasingly popular;by September 2011,the total daily sales at Taobao______ had amounted to 935 million yuan,which had even overtaken the daily total sales of Hong Kong.
The teacher commanded that the students __________ the classroom before he returned.
Before the tourists set off, they spent much time setting a limit __________ the expenses of the trip.
There is a limit __________ people's life, but no limit __________ the knowledge.
Unfortunately, the research was limited __________ increasing economic profits,__________ protecting the environment.
They are trying to find a new way to __________ the spread of AIDS.