问题
选择题
After 15 years in the USA, he finally decided to ________ American citizenship.
A．concentrate on
B．apply for
C．put off
D．lead to
答案
B
题目分析：A. concentrate on全神贯注于，B. apply for申请， C. put off推迟，D. lead to导致，句意：--在美国15年后，他最后决定申请美国公民。根据句意选B。