(1) She bought a ____ (bath) suit last Sunday.(2)I like doing some ____ (shop) at weekends.(3)She hasn't ____ (feed) the cat yet.(4)There are about ten ____ (well) in that village.(5)Has the camera been____ (pack) yet?
关于电磁现象,下列说法正确的是( )
已知点A的坐标为(a,b),点A在第一象限,O为坐标原点,连接OA,将线段OA绕点O按逆时针方向旋转90°得OA1,则点A1的坐标为( )