In the United States, Father's Day falls on ___ third Sunday in ____ June.
A:the; 不填
B:the; a
C:不填; the
D:a; 不填
合并同类项:4a2+3b2+2ab﹣4a2﹣6b2.
如图,一个绕过圆心的轴匀速转动的圆盘上有a、b、c三点,已知oc= 12 oa,则下列说法中错误的是( )