请把钥匙插入锁孔。

Please ___insert the key into the keyhole.

请在这份报告中插入一张图表来说明数据。

Please ___insert a chart in this report to illustrate the data.

他适时地插嘴提出了一条建议，解决了大家的困惑。

He ___inserted a suggestion at the right moment, which solved everyone's confusion.