Therearesomehealthproblemsthat,when

問題詳情：

       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　考查非謂語動詞。在該句中，邏輯主語是some health problems，與 treat之間構成被動關係，所以用過去分詞，when not treated in time是when they are not treated in time 的省略，選A項。B、C和D項雖然也都表示被動，但B項強調正在進行的動作；C項強調將來的動作；D項則強調已經完成的動作，故都排除。

知識點：非謂語動詞

題型：選擇題