下列各组物质在溶液中能大量共存且形成无色溶液的是【   】

A．NaCl BaCl₂ Na₂CO₃

B．KNO₃ HCl CaCl₂

C．H₂SO₄CuCl₂ NaNO₃

D．NaOH HNO₃ NH₄NO₃

What is this talk mainly about

A．How historical events affected an art movement.

B．How artists can influence economic conditions.

C．Why a certain art movement failed to become popular.

D．How valuable paintings were lost during wartime.