—Who did English homework better, Leo or Nick?                  

—Leo is more careful. I think Leo did _____Nick.                 [ ]

A. as good as              

B. as well as                

C. better than              

D. worse than

下列各物质在空气中，质量会发生变化且只发生物理变化的是 [ ]

A．Na₂CO₃·10H₂O

B．CuSO₄

C．烧碱

D．浓盐酸