单项选择题
—Aren't you Mary's sister —（）. I'm her aunt.
A. Yes I am B. No I'm not C. Yes I'm not D. No I am
单项选择题 （）Yellow River is the second longest river in our country.
单项选择题 My little sister is so tired, she can hardly walk,（）
单项选择题 It（）us two hours walk to get to our school.
