问题
选择题
People in Nome all had diphtheria, a disease that spreads very fast. If ________, it would produce a powerful poison that would kill the patient.
A．untreating
B．to untreat
C．untreated
D．untreat
答案
答案：C
这题考查if条件句的省略，如果主从句的主语一致，可以省略从句的主语和be动词，这句话的if条件句是省略的，所以是主语a disease被省略了，a disease和untreat之间是被动关系，所以用C。