In the USA, he made a lot of friends English well to make himself .
A. learn; understand
B. to learn; understood
C. learning; understand
D. learned; understood
网友回答
A. learn; understand
(答案→)B. to learn; understood
C. learning; understand
D. learned; understood
解析： 第一个空是不定式作目的状语；第二个空是过去分词作宾补。