Answer : Are they watching a movie now?
为什么用are:
-因为they是他们(多人)的意思,这样就排除了is,am,was
-因为now是现在的意思,所以自然只能用are
为什么是watching:
-is,am,are,was,were后面的动词只能是continuous tense(正在) / past participant tense (被动)
希望有帮到你~
Are they watching a movie now?