已知大圆的半径为5，小圆的半径为3，两圆圆心距为7，则这两圆的位置关系为【 ▲ 】
A．外离
B．外切
C．相交
D．内含
答案：C
两圆相切。故选C
-Susan stays alone in the classroom and looks sad.
-__________ to her?[ ]
A. What happens
B. What has happened
C. What is happening
D. What was happening
怎样用沼液防治蔬菜蚜虫？
两圆相切。故选C
两圆相切。故选C