Question

3.        to speak when the audience interrupted him. (Hardly)

他刚一开始说话，就有观众打断了他。

Answer 1

3. Hardly had he begun所给选词Hardly是大写开头的，表明其应位于句首。 hardly... when...为特别句型，hardly位于句首时，主句部分倒装，且谓语应用过去完成时。