题干
Lisa is going to stay ______ with her grandparents on Saturday morning.
A：in the country
B：at the country
C：in country
D：at country
答案(点此获取答案解析）
A
Lisa is going to stay ______ with her grandparents on Saturday morning.
A：in the country
B：at the country
C：in country
D：at country
中，已知平面区域
，则平面区域
的面积为 （ ）