A:Never mind
B:Of course not
C:Yes, I do
D:That’s all right
已知圆系方程(x﹣m)2+(y﹣2m)2=5(m∈R,m为参数),这些圆的公切线方程为____
Helen ____ (study) English, Chinese. Maths, Science and Art at school.
性状是指( )