你好,我的理解是：首先这是定语从句,第一句话IlikemusicthatIcansing alongwith,that 这个词在从句中做的是宾语,而that指代前面的music.I can sing along with that 也就是说把music 还原到从句中就是sing along with music.因为sing along本身是不及物的,也就是不能直接接宾语,所以后面必须接个with才能接宾语.
同理,把music还原到dance to 的后面.Ican dance to the music.dance 不能直接接宾语music所以要加介词to.
Rose likes music that's quiet ahd gentle.that's是that is 缩写.Rose likes music that is quiet ahd gentle.别的定语从句也可以加,这只是个缩写.
我现只是一名在校大学生,知识讲解的有偏差还请谅解,希望能够帮助到您,谢谢!