This is an illness that may result in total blindness if .A. being left untreatedB. left u

问题补充：

This is an illness that may result in total blindness if .

A. being left untreated

B. left untreated

C. not left treating

D. not having left untreated

答案：

A. being left untreated

(答案→)B. left untreated

C. not left treating

D. not having left untreated

解析：要做好省略结构的题目，考生必须明白省略了哪些成分，学会将句子整合。如本题从句可补全为：if it is left untreated。另外，本题的另一个难点是：学生对untreated的用法搞不明白。老师可将此结构先用主动形表达，即People left the illness untreated.此处untreated作宾语补足语，与illness构成被动关系，转换成被动句为：The illness is left untreated.本句话语意为：如果不治疗，这病可能会造成双目失明。