从历史上看，美国帮助的国家往往在最后反咬一口。

History shows that the assistance the US gives to any of these countries end up backfiring in everyone's face.

海王星有时是一面双刃剑，你要对此警觉防止被反咬一口。

With Neptune, sometimes there's a double-edge sword that you need to be aware of so that it doesn't come up and bite you.

这些毒蛇被攻击时自然会反咬一口，那么这就引出了一个问题：眼镜王蛇是如何维持这样一种明显高风险的生活方式的？

These snakes bite when attacked, of course, which raises the question: How does the king cobra maintain such an apparently high-risk lifestyle?

记得几年前，电视上经常报道这样的事：有的老人摔倒了，好心人帮忙将老人送进医院，可最后却被老人的家属反咬一口；

Remember a few years ago, TV often report such things: some of the old man fell down, and the man to help the old man to the hospital, but finally the old man family members bite;

敦豪方面说它肯定会反咬一口的，反咬的方式是利用它和联邦联合快递合同的收入，还有就是通过重新设计其地面快递网络以此来提供更加便宜的服务，这将是联邦联合快递和联邦快递服务替代品。

DHL says it will bite back by using the savings from the UPS deal and from reconfiguring its ground network to offer a cheaper alternative to services from UPS and FedEx.