提高英语水平的终极途径是一个字：用。学而不用，最终下场就是忘掉。最近新冠肺炎(covid-19)肆虐，一句“非必要不出行”说的较多。我说过，“非必要不出行”应当改为“非必须不出行”。至于英语里是如何表达“非必须不出行”这个意思的呢，是我今天要讲的内容。

先看选自时评的有关例句：

1）基本的表达：to ban nonessential travels.

“非必须不出行”在英语里使用的词是nonessential,汉语的意思是非必需的。Nonessential是从essential派出来的，essential的意思是基本的，必不可少的，必需的。但是英语里是一般的叙述，汉语里则是口号式的。

例句：(CNN) — The European Union recommended on Monday that Americans should be banned from nonessential travel to its member states after a rise in Covid-19 cases in the United States.

例句：The guidance, which also now applies to Israel, Kosovo, Lebanon, Montenegro, and the Republic of North Macedonia, is non-binding for EU member states. That means it remains up to each individual EU country to decide whether to allow "nonessential travel to the EU for fully vaccinated travelers."

在看完例句后，英文表达“非必须不出行”就出来了：

1）Travel only when essential.

2）Nonessential travel prohibited.

3）No traveling on nonessential business.

当然，期待你造出自己的更好的英文句子。