用方框中所给单词的适当形式填空。(每小题1分，共5分)

thin  twelve  cost  south  develop

 
Mr. Green lives on the __________ floor of the building.
After exercising for a few months, she is a little           than before.
How much does it           to fly to Shanghai from Fuzhou?
Many foreigners are surprised at the rapid _______________ of China.
It rained heavily in the           of Fujian Province last week.