大全637at least fifty percent less likely than？？

637.Several studies have found that the coronary patients who exercise most actively have half or less than half the chance of dying of a heart attack as those who are sedentary.
(A) have half or less than half the chance of dying of a heart attack as those who are sedentary
(B) have half the chance, or less, of dying of a heart attack than those who are sedentary do
(C) have half the chance that they will die of a heart attack, or less, than those who are sedentary do
(D) are at least fifty percent less likely to die of a heart attack as those who are sedentary
(E) are at least fifty percent less likely than those who are sedentary to die of a heart attack

请教这一题，答案 E

不明白的是 fifty percent less likely than可能少于50%，前面又加了一个at least至少可能性少于？？？不懂呢？？？？

至少A是大于等于A的意思 ，至少少于50%怎么可能是小于等于50%的意思呢
又是小于，又是大于等于，绕不出来呢

at least fifty percent（例如 75%) less likely（不可能) to die(得病）= 原题中, less than half (例如25%)of 得病;

不要细想，越想越绕

don't be. seperate it into two steps so that you feel clear:

step one: "50% less likely than...."

step two: "at least" is to modify "50%",

"(at least) 50% less likely than" is a clear and correct structure. 

呵呵，这个明白了，可是能不能解释C为什么不对吗？have the chance that....应该没有错的阿

C) have half the chance that they will die of a heart attack, or less, than those who are sedentary do

C is wrong because the term "or less" is in the wrong position.

还是不明白，按你的第一步，小于50%的可能性

第二步，至少小于50%的可能性，

我还是没想明白这时大于等于还是小于等于。

能再讲一下吗？？？