汽车拉着拖车在水平道路上沿着直线加速行驶,根据牛顿运动定律,以下说法正确的是( )
A:汽车能拉着拖车加速前进,是因为汽车拉拖车的力大于拖车拉汽车的力
B:加速前进时,汽车对拖车的拉力大小与拖车对汽车的拉力大小相等
C:汽车先对拖车施加拉力,然后才产生拖车对汽车的拉力
D:汽车对拖车对拉力大小与拖车所受地面对它的摩擦力大小相等
若b<0,则二次函数y=x2+bx-1的图象的顶点在( )
用括号内所给词的适当形式填空,使句意完整I'm going to be a____ (report) when 1 grow up. I like meeting different people every day,China has become much____ (strong) than before. We' re all proud of her.Look! The children are playing ____ (happy) in the park.Of all the vegetables, I like____ (tomato) best.Stop____ ( talk), please,Let' s begin our meeting.