某型号汽车发动机的额定功率为6×104W,在水平路面上匀速行驶时受到的阻力是2000N.在额定功率下,当汽
车匀速行驶时,则发动机所提供的牵引力大小是____ N,行驶速度是____ .
Lucy often goes to school __________ breakfast. It's bad for her health.
宋辽、宋夏和议中共同内容有( )