根据图片及首字母提示补全下列单词，使短文内容完整、连贯。

      Today is Christmas Day. My  1.h____________ is very beautiful. We have a

big  2.C____________ tree with a  3.s____________ on the top.

In the morning, I received (收到) many gifts, and Christmas  4.c____________.

I was very happy. " Who brought me these gifts, Mum? " I asked. “  5.S____________

brought you last night." said Mum. But I don't think so. I think my Mum and Dad brought them.

They love me very much.

下列说法不正确的是( )。

A．只有安全边际才能为企业提供利润

B．盈亏临界点销售额扣除变动成本后只能为企业收回固定成本

C．安全边际部分的销售减去其自身变动成本后成为企业利润

D．安全边际中的边际贡献不等于企业利润