A:①③
B:②③
C:①④
D:③④
质子和α粒子以相同的动能垂直磁场方向射入同一匀强磁场,它们运动轨迹半径之比Rp:Rα=____,运动周期之比Tp:Tα=____.
My friend Tom lives on Sun Street. It is near his school. He usually goes to school on foot. But sometimes he goes to school by bike. His father is a doctor. He goes to work by car. His mother is a teacher. She teaches English. She goes to work by metro. Today is Sunday. Tom doesn't have any lessons. He wants to go to Nanjing by train.
下面语段中划线的词语,使用不恰当的一项是( )近年来,重视中国传统文化的呼声越来越高,但与此形成鲜明对比的是传统文化在民间却渐行渐远。对于这个问题,仁者见仁,智者见智:有人认为此前一些传统节日没有被列为法定节日是导致传统文化传承危机的重要原因;但也有人认为这不能归咎于传统节日没有成为法定假日,春节一直都是法定假日,但其间的一些传统习俗却改弦易辙了。