Therearesomehealthproblemsthat,when

问题详情：

       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 having been treated

【回答】

A　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，所以用过去分词，when not treated in time是when they are not treated in time 的省略，选A项。B、C和D项虽然也都表示被动，但B项强调正在进行的动作；C项强调将来的动作；D项则强调已经完成的动作，故都排除。

知识点：非谓语动词

题型：选择题