beginning-of-tape mark

例句：

1. 1.This tape has a beginning-of-tape mark at the beginning of the recording.
   这条磁带在录音的开头有一个磁带开始标记。
2. 2. The engineer marked the beginning-of-tape on the tape to indicate the start of the recording.
   工程师在磁带上标出了磁带开始标记，以指示录音的开始。
3. 3. During the editing process, it's important to note that the beginning-of-tape mark is not alwayspresent.
   在编辑过程中，要注意的是，磁带开始标记并不总是存在的。