题干
I bought a dress for you only 10 dollars in a sale; it was a real _____.
A：exchange
B：bargai
C：trade
D：busine
答案(点此获取答案解析）
B
的图象向左平移
个长度单位，再保持所有点的纵坐标不变
，得到函数
的图象，则使