大全516，请教

1.        Most large companies prefer customized computer software because it can be molded to fit the way a company does business, when off-the-shelf software often requires the company to alter its procedures to fit the software.

(A) when

(B) since

(C) whereas

(D) because（C）

(E) insofar as

请问如何选择，我觉得每个选择都说的过去

whereas 用在主句后，加逗号，表示对比，相当于while

另whereas也可以用在句首表示“尽管，虽然”

我也有同样的疑问

我觉得表示原因也可以，前果后因，从逻辑的角度讲，应该也是对的。

prefer customized computer software , 因为 off-the-shelf software .....

再仔细想一下，还是whereas好，因为前面已经有了一个because来解释为什么prefer customized computer software. 所以后面再去解释一遍，就显得多余了。这里理解为转折的话，更合理些。

whereas 比较正式， 有对比的意思，　而其他的则无，

 longman解释： used to say that although something is true of one thing, it is not true of another

The old system was fairly complicated whereas the new system is really very simple.

 Whereas the city spent over $1 billion on its museums and stadium, it failed to look after its schools

since:
        
used to give the reason for something
Since you are unable to answer, perhaps we should ask someone else.

in so far as/insofar as/in as far as
            
formal to the degree that
The research suggests that the drug will be successful, in so far as one can draw conclusions from such a small sample size.