Before going abroad he devoted all he could his oral English.A. improve。mB. to improveC.

问题补充：

Before going abroad he devoted all he could his oral English.

A. improve。m

B. to improve

C. improving

D. to improving

答案：

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。