问题补充：
The mother is very glad; her baby is beginning .
A. understanding what she means
B. to understand that she meant
C. to understand what she means
D. noticing what she means ,
答案：
A. understanding what she means
B. to understand that she meant
(答案→)C. to understand what she means
D. noticing what she means ,
解析：考查begin的用法：begin后面一般可以接不定式或动名词做宾语，但如果做宾语的动词是表示心理活动的词，就用动名词做宾语，句意：妈妈很高兴，她的孩子开始理解她的意思了。选C。
