题干
B
A Mexican boy doesn't get any help from his family for his dreams of playing music．But an old guitar brings him to a new world where everything changes．
Miguel is a 12-year-old boy living in a small village in Mexico．His idol(偶像)is a great guitar player called Ernesto de la Cruz．Miguel dreams to become a musician like him．
However, his family are against it. When he secretly joins a talent show，his grandmother finds him out and destroys his guitar．He is angry and steals an old guitar to play in the show．
Then something magical happens! The guitar brings him to a new world. Everyone who has ever died lives there．He sees his dead family members，like his aunts and uncles．They say they can help Miguel to go back，but he has to give up his musical dream．
Miguel doesn't want to．He meets a friend called Hector who helps him find a guitar．They go to a music contest together．What happens next?
The answer is in the movie，and you can go to see it．It has come out in China since Nov 24，201 7．There are no ghosts in the real world．But the movie's world is full of imagination．
C（气）＋D（气），当下列物理量不再变化时，不能表明反应已达平衡的是（ ）