their homework these three students have to stay in the classroom for another thirty min

问题补充：

their homework, these three students have to stay in the classroom for another thirty minutes.

A. Not finishing

B. Not finished

C. Having not finished

D. Not having finished

答案：

A. Not finishing

B. Not finished

C. Having not finished

(答案→)D. Not having finished

解析：考查非谓语动词。句意：（由于）没有完成他们的作业，这些学生不得不在教室里再呆三十分钟。现在分词作原因状语表示正在进行的伴随性动作，如果动作发生在谓语动词之前，则用完成时态的过去分词，故选D。