11. 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）

(E) are at least fifty percent less likely than those who are sedentary to die of a heart attack

这道题E是对的 但B的错误在哪儿呢 不是特别清楚B的结构