enough as to 有错吗

manxueer1632

41. GWD-23-Q13
Researchers hypothesize that granitic soil is the ideal construction material for the desert tortoise because it is not so hard that it makes burrowing difficult or so soft that it could cause tunnels to collapse.
A.so hard that it makes burrowing difficult or so soft that it could cause
B.hard enough to make burrowing difficult or soft enough as to cause
C.so hard as to make burrowing difficult or soft enough so it causes
D.as hard as to make burrowing difficult or as soft as to cause
E.too hard, making burrowing difficult, nor too soft, so as to cause

答案选A，看了不少帖子都纠结D，可是B为什么错呢？

bejamin1111

b不符合逻辑，原句的意思是这种soil不是那么硬，所以能够打洞，同时也不是那么软，不会使tunnel坍塌，强调的是软硬适中。而b中，enough意思是as much as required，这种东西足够硬，又足够软。。。这什么逻辑，你感受下。

manxueer1632

哦~明白了，谢谢回答~