Having lived in China for 8 years Helen has a good of both English and Chinese.A. abilit

问题补充：

Having lived in China for 8 years, Helen has a good of both English and Chinese.

A. ability

B. guidance

C. command

D. program

答案：

A. ability

B. guidance

(答案→)C. command

D. program

解析：考查名词和词组：A. ability能力，B. guidance指导，C. command命令，掌握，have a good command of“精通”，D. program节目，课程，句意：在中国生活了8年，海伦精通英语和汉语。选C。