1. Expression: have a tiger by the tail

Explanation: To be involved with someone or something that is powerful and could become troublesome or threatening. （遭遇劲敌）

Example：Once you start using heroin, you'll have a tiger by the tail. If you get hooked and you'll need more and more. It'll cost you more money and you might have to steal to support the habit.

你一旦开始用海洛因，就很难找到退路。上瘾之后，需要量越来越大，需要更多的钱，甚至还要为了满足毒瘾去偷窃。

He found he had a tiger by the tail. Despite his promise he had to raise taxes to cope with the deficit. And this helped Bill Clinton beat him in his try for re-election in 1992.

他遭遇劲敌了——为了应付赤字顾不了自己的承诺了，增加征税，结果最终在连任竞选中被Bill Clinton击败。

Now that I have to work closely with the CEO on this project, I feel like I have a tiger by the tail.

因为我必须在这个项目上与首席执行官密切合作，所以我感觉我遭遇劲敌。

You've had a tiger by the tail ever since you agreed to finish that big project.

自从你答应完成那个大项目以来，你就一直处于被动地位。

2. Expression: catch a tiger by the tail

Explanation: To become or find oneself responsible for something risky, precarious, or unsafe. （骑虎难下，处境岌岌可危）

Example : You're taking on an organization with reserves you know nothing about. How do you know you won't be catching a tiger by the tail?

你所面对的是一个你一无所知的组织，你怎么知道你将来就不骑虎难下呢？

Anybody who experiments with drugs is catching a tiger by the tail.

任何做药物试验的人都要担风险。

It has now become obvious that our country has been catching a tiger by the tail with our military intervention in this region—it was foolish to get involved, but it would be catastrophic to leave now.

现在很明显，由于我们的国家对这个地区的军事进行干预，所以现在是骑虎难下——介入是愚蠢的，但现在离开将是灾难性的。

I believe that Hitler is catching a tiger by the tail in trying to keep all Europe under control by sheer force.

我相信Hitler企图强行用武力来控制整个欧洲，这是骑虎难下。