prep 1-131

131.
            (31462-!-item-!-188;#058&004501)

The particular design of muscles and bones in the neck and limbs of the turtle allow that it can draw in its exposed parts such that an attacker can find nothing but hard shell to bite.

(A) allow that it can draw in its exposed parts such that

(B) allow it to draw in its exposed parts, and so

(C) allows for it to draw in its exposed parts and that

(D) allows that it can draw in its exposed parts, and so

(E) allows it to draw in its exposed parts, so that

答案是E没问题。。。

可是看NN的解释说B,D中and,so两个连词重复使用，但是刚才查字典发现是有and so这个固定结构的，表示and therefore,Madeira has an ideal climate, and so it is not surprising that it has become a tourist paradise.
　           This was considered to be a religious issue and so to be a matter for the church courts

这样看，and so在这里是没有错的呀，那么D选项为什么不可以呢？除了有些罗索以外。

期待NN指点！！

主语是design! 谓语用单数! AB排除!

请看文章意思，allow to 比allow that好

另外，尽管and so再对，也有歧义：and表示平行还是and therefore?---------请注意GMAT SC的精髓，不是语法。