问题补充：
The kind lady devoted all her life to those homeless children.
A. help
B. helping
C. be helping
D. being helped
答案：
A. help
(答案→)B. helping
C. be helping
D. being helped
解析：句意：这位善良的女士把她的一生致力于帮助那些无家可归的孩子们。Devote to是固定用法，意思是致力于，to是介词，后面要用动词的-ing形式，选B。
