置顶插入Place on Top

置顶插入（Place on Top）把源片段放到时间线上一层的新轨道上，常用于把 B-roll 镜头叠在访谈画面上。

• 把源片段拖到时间线检视器工具栏的 Place on Top 按钮上，片段会落到上方的覆盖轨道（V2）。
• 这样主画面（如采访）保留在 V1，B-roll 镜头以 cutaway 的方式叠在上面。
• 快捷键是 F12。
• 本课也用它把配乐放到新的音频轨道上。

Place on Top puts a source clip onto a new track above the timeline, typically to overlay B-roll onto the main footage.

• Drag the clip onto the Place on Top button in the timeline viewer toolbar, and it lands on an upper track such as V2.
• The main footage stays on V1 while the B-roll plays above it as a cutaway.
• The shortcut is F12.
• In this lesson it is also used to drop the music onto a new audio track.