be responsible for
A. 因…而受到责备
B. 因…而感激
C. 控诉…
D. 对…有责任
apply for
A. 申请
B. 运用
C. 为…道歉
D. 申请信
It is a little difficult for me to____the problem.
A. answer
B. answering
C. answered
D. answers
Qian Xuesen devoted all his life to______scientific research.
A. do
B. doing
C. did
D. does