问题补充：
20. What can I do for you? or May I help you? is a pet phrase used by .
A. an assistant engineer
B. an assistant manager
C. a helper
D. a shop assistant
答案：
A. an assistant engineer
B. an assistant manager
C. a helper
D. a shop assistant
解析：
700字范文，内容丰富有趣，生活中的好帮手！
