问题补充：
Whether you believe it or not, it is that causes your illness.
A. because of your overweight
B. you are so overweight
C. because you are overweight
D. your being overweight
答案：
A. because of your overweight
B. you are so overweight
C. because you are overweight
(答案→)D. your being overweight
解析：考查动名词的复合结构作主语。it is that causes your illness是it is…that的强调句型，去掉it is that可知句子缺少主语，A,C表原因，不能作主语；B项前要加that，变成that引导的主语从句。所以选D。
