单项选择题
A. He has always lived in America. B. He has been in America for three years. C. He visited America three years ago. D. He has come to America to do research on advertising.
A. how to adapt to the environment B. how to defeat something dangerous C. how to forecast weather D. how to control moving objects
A. to help her father with business B. to help Steven choose a bike C. to buy herself a bike D. to work part time as a salesclerk