Ngữ pháp toefl itp-Mạo từ a và an P3

Since the beginning of this century, the United States government has played an role in the supervision and use of the nation’s natural resources.

Vervet mons have a well-developed systems vocal communication.

Mount Rushmore National Memorial in South Dakota has a heads of four presidents of the United States carved into its face.

The Montreal International Exposition, “Expo 67,” was applauded for displaying an degree of taste superior to that of similar expositions.

The Rodeo Association of America, formed in 1929, set up a system points for determining the national rodeo champions.