船员们正在桅杆顶端更换新的导航灯。

The crew is replacing the navigation light on the ___mastheads.

这本杂志的报头设计得非常醒目。

The ___mastheads of this magazine are designed to be very eye-catching.

杂志的版权页上印有完整的编辑部名单。

The magazine's ___masthead includes all the editorial staff members.