Question

There are some health problems that, when ______ in time, can become bigger ones later on.

A. not treated              B. not being treated

C. not to be treated       D. not have been treated

Answer

A

【解析】

试题分析：考查非谓语动词。在该句中，逻辑主语是some health problems，与 treat之间构成被动关系，表示“没有被治疗的话”，所以用过去分词，这里答案选A项。B，C和D项虽然也都表示“被动“，但B项意为“正在被治疗，强调正在进行的动作”；C项意为“将要被治疗，意为将来的动作”；D项则意为“早就已经被治疗，强调已经完成”，故都排除。