12.So absorbed__________in her work that she didn't realize I was behind her.

A．did she

B．was she

C．she did

D．she was

某企业甲、乙两组工人人数和工资资料如下：

请根据上述资料计算分析该企业总平均工资的变化情况，逐项填答下列问题。

以下公式正确的是（）。

A．A

B．B

C．C

D．D