Before going abroad he devoted all he could his oral English.
A. improve。m
B. to improve
C. improving
D. to improving
网友回答
A. improve。m
B. to improve
C. improving
(答案→)D. to improving
解析：注意两点：一是 devote … to … 是固定搭配，意为“把……贡献给……”；二是其中的 to 是介词，不是不定式符号，后接动词时要用动名词。