A:反应前后本身质量不变
B:反应前后化学性质不变
C:一定加快化学反应速率
D:可能减慢化学反应速率
____ ____ ____
一根质量分布均匀的铅笔芯,用去三分之一后,其质量____ ,密度____ .(以上两空均填“增大”、“不变”或“减小”)
⑴I need a train ticket from Beijing to Shanghai. ____ A.
⑵Danny doesn't like fruit. ____ B.
⑶Danny needs a camera. ____ C.
⑷I don't need any winter clothes. ____ D.
⑸Danny likes roses. ____ E.