帮忙解一下并分析一下，谢谢

D
一般现在是与现在完成时在时间概念上是一样的，在很多的英语表达中，一般现在是与现在完成时相互替换，大多基于说话人的习惯。该题中的It is five days 可以替换为It has been five days。 因此后面应该是D
It is five days 与It has been five days 的区别是“体”上的区别，而不是“时”的区别。请参阅：《英语时与体的认知轨迹研究〉一文。

D

选D，意思是我们来这里已经有五天了。

D

since的四种用法

1) since +过去一个时间点 (如具体的年、月、日期、钟点、1980, last month, half past six)。
I have been here since 1989.

2) since +一段时间+ ago
I have been here since five months ago.

3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.

4) It is +一段时间+ since从句
It is two years since I became a postgraduate student.

D 我们已经来了五天
since与现在时或过去完成时连用表明从..以后或自..以来如
I haven't eaten since breakfast.(早饭以后我还没吃过东西呢)

全都错

本身句子有问题
如果是A. when那么要说it was five days ago when we came her
如果是D. since那么要说it has been five days since we came here

至于另外两个答案根本就