直线与圆弧切点的计算方法有（）计算法、精确作图法两种。
A.直接
B.微分
C.积分
D.间接
参考答案：A
Peter and John are Mr Brown's sons. They are the same age (一样大) and look the same.
I think they are _____. [ ]
A. a twin
B. twin sisters
C. cousins
D. twin brothers
违约责任
