擅自的英文：
unauthorized

They were trespassing on private property.
他们擅自闯入私人房屋。

Abuse of distress
擅自使用扣押或查抄的财产

Vehicles parked here without authorisation will be wheel clamped
未经允许,擅自停车者,将予以扣留

The children entered the concert without permission.
小朋友擅自进入音乐会。

Building occupied by squatters(squatter )
被擅自占用的建筑物

Who are they to tamper with the rules of the game?
他们凭什么擅自修改比赛规则？

You are extremely audacious to open out a mine!
你竟敢擅自开矿，真是胆大妄为。

Someone's been meddling with my CD player.
有人擅自碰过我的雷射唱机了。

The guard deserted his post.
卫兵擅自离开了他的岗位。

You could be prosecuted for trespass.
你可能会因为擅自闯入而受到起诉。

Damages due to misuse and unauthorized modification of hardware.
人为因素造成之故障、损坏或改装。

No unauthorized person is allowed in the room while the examination is in progress.
当考试进行时，未经许可者不得入内。

Unchecked (unauthorized) flow of population (from the countryside to the cities)
盲流人口

Failures to prohibit unauthorized departmental coffers repeatedly.
各种“小金库”屡禁不止。

Unauthorized emails are treated as junk after a period of time.
未被授权的电子邮件时间的时期如垃圾邮件被对待。