—Will you come ________ have a drink with me?—I'd love to, _________ I'm too busy these days.
A:and, or
B:and, but
C:or, but
D:or, and
等差数列an, an=2n+1,则a3= ( )
如图所示,一波源在绳的左端发生半个波1,频率为f1,振幅为A1;同时另一波源在绳的右端发生半个波2,频率为f2,振幅为A2。图中AP=PB,由图可知( )
如图,下面两幅图选自《蔡志忠漫画》,它们分别反映了战国时期诸子百家中哪一学派的思想主张 图一 图二