单项选择题
— What can I do for you? —（）
A.I want a kilo of pears. B.You can do in your own way. C.Thanks. D.Excuseme.I’m busy.
单项选择题 She's part of a team of scientists who are（）upon cancer research.
单项选择题 Tourism has（）agriculture as the nation's main industry.
单项选择题 I cannot tell the（）difference between the twins.
