A district reserves the right to keep something in place.

一个地区拥有保留某些东西的权利。

You keep something in your mind, you remember it, right, until you need it.

把某件事情装在脑子里，就是需要记住这件事情，直到需要用得到的时候。

It's a noun, it means keeping something in good condition, by making repairs or correcting problems.

这是一个名词，它的意思是通过维修或纠正问题，使某物保持良好状态。

" Preservation" means to keep something in its current condition.

“保存”是指将某物保持在当前状态。

Yeah, to keep people out. Or to keep something in.

防止人类进去 或让某东西进去。

" To preserve" (preserve) means to protect something or to keep something in its current condition.

“保存” （preserve）的意思是保护某物或使某物保持现状。

You can also keep something " in mind" , not only a person " in mind" .

你也可以“记住”一些东西，而不仅仅是“记住”一个人。

The expression, to keep something in mind, means the same as remember – be sure to consider.

to keep something in mind 的表达方式与 remember 意思相同——一定要考虑。

I should mention is a small piece of usually metal that you put into something – you stick into something, usually to keep something in place.

，我应该提到的是一小块通常是金属的东西， 你可以把它放进什么东西里——你插在什么东西上， 通常是为了把东西固定在适当的位置。

A fence is designed either to keep something in, such as your animals so they don't escape, or to keep something out, such as your neighbors.

栅栏的设计要么是为了将某些东西挡在里面，比如你的动物， 这样它们就不会逃跑， 要么是为了把东西挡在外面， 比如你的邻居。

When we say you " keep (something) in check" we mean you're controlling it so that it doesn't get worse;it doesn't get so serious that it could kill you, in this case.

当我们说你“控制（某事）”时，我们的意思是你正在控制它，这样它就不会变得更糟；在这种情况下，它不会变得严重到可能要了你的命。