Mr. Wang made up his mind to devote all he could his oral English before going abroad. A.

问题补充：

Mr. Wang made up his mind to devote all he could his oral English before going abroad.

A. improve

B. to improve

C. improving

D. to improving

答案：

A. improveB. to improveC. improving(答案→)D. to improving

解析：此题中包含固定短语devote…to，其中to 为介词，后面应接定名词。动词devote后接的宾语为all，all又为先行词，后又包含一个定语从句：he could (do)。此题很容易误以为could后应接动词原形，而易选为A。答案为D。