在2008年，我从没有在上山时跑过，所以我觉得没有必要训练向山上跑。

I never ran uphill in 2008, so I decided that I shouldn't practice running uphill in my training.

youdao

所以完全没有必要担心你的健康会变差，训练会落后，或者产生自己根本不适合跑步这样的念头。

So don't worry that you're losing fitness, falling behind in your training, or that you're just not cut out to be a runner.

youdao

进行这项培训会议上，你可能会想用警犬训练衣领，但它是没有必要的。

For this training session, you might want to use a dog training collar, but it is not necessary.

youdao