已知l是直线，α、β是两个不同的平面，则下列命题中的真命题是[ ]

A.若l∥α，l∥β，α∥β

B.若α⊥β，l∥α，则l⊥β

C.若l⊥α，l∥β，则α⊥β

D.若l∥α，α∥β，则l∥β

— Where's the library?

— _____.         [ ]

A. Read books      

B. It's big          

C. It's on the first floor