Until this week, every attempt to tighten up the law had failed.

到本周为止，一切严格执法的努力都失败了。

It's important to tighten up the wheels properly, otherwise they vibrate loose and fall off.

把车轮拧紧很重要，否则它们会振动而松脱。

Tighten up with the supplied wrench.

使用扳手固定。

Why does China tighten up its visa policies?

为什么中国收紧了签证政策？

We need to tighten up security at the prison.

我们必须加强监狱的安全性。