I rarely used the four physical buttons at the bottom of the screen (in portrait mode) for locking the screen, browsing, returning to a previous screen, and returning to the home screen.

屏幕底部的四个物理按键在肖像模式下分别用于锁定屏幕、浏览、返回上一屏幕以及并返回主屏幕，但我很少使用。

youdao

We just wish LG could tweak the player so that the lock key doesn't pause music before locking the screen.

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The left side sports the power button, a lever for locking screen orientation and a volume rocker, while the top has the 2-megapixel front camera and 5-megapixel rear-facing shooter.

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Then, after locking the device, attempting to unlock it will send you to the palm authentication screen, seen above, where (hopefully) only your mitts will be able to gain access.

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