—Did you see the film star?

—________，I couldn't make it. I was delayed by the traffic.

A．In fact

B．Luckily

C．Naturally

D．Unfortunately

下列说法不正确的是

A．原子核外电子离核越近的能量越低

B．得电子难的原子，失电子一定容易

C．一种元素原子的核电荷数与其原子序数在数值上相等

D．在同一种物质中同种元素的化合价可能不相同