In January , 2004, the United States successfully launched “Spirit”, a Mars Exploration Rover, _____ a new milestone in the history of mankind.
A. it marked B. marking C. marked D. to mark
In January , 2004, the United States successfully launched “Spirit”, a Mars Exploration Rover, _____ a new milestone in the history of mankind.
A. it marked B. marking C. marked D. to mark
B