The city’s underground _____ more people than the buses.

A series of stimulus policies and supportive measures taken by the government _____ to promote change in the economic environment in this area.

My parents have promised to come to see me before I ____for Africa.

Great changes have taken place in China since the People’s Republic of China     in 1949．

—I guess you can buy such a smart phone for 300 dollars. —I could just two months ago，but the price ________ by 20%.