the disease will produce a powder poison that will kill the patient.A. If it untreatedB

问题补充：

, the disease will produce a powder poison that will kill the patient.

A. If it untreated

B. If is untreated

C. If being untreated

D. If untreated

答案：

A. If it untreated

B. If is untreated

C. If being untreated

(答案→)D. If untreated

解析：句意：如果不得到治疗，这种疾病将会产生杀死病人的粉末状病毒。完整形式为：Ifthediseasediphtheriaisuntreated…，从句的主语与be动词省略了，选D。