题干
Can you help me buy______sweets, please?
A：a piece of
B：a packet of
C：a copy of
D：a cake of
答案(点此获取答案解析）
B
Can you help me buy______sweets, please?
A：a piece of
B：a packet of
C：a copy of
D：a cake of
的图象在点
处的切线方程是
，则
（ ）