到底用英文怎么表达？

　　人们到底为什么总敞着门呢？

　　Why oh why do people keep leaving the door open?

　　他们到底认为自己在做什么？

　　What in the world did they think they were doing?

　　你只好硬着头皮撑到底了。

　　You're just going to have to tough it out.

　　我保证我会坚持到底。

　　I promise I am in this for the long haul.

　　警方正设法查清到底发生了什么。

　　The police are trying to ascertain what really happened.

　　他们到底出了什么事，到现在仍可以说是个谜。

　　What happened to them remains somewhat of a mystery.

　　极少受训者坚持到底了。

　　Very few of the trainees have stayed the course.

　　请原谅我的无知，这家公司到底是干什么的？

　　Forgive my ignorance, but what exactly does the company do?

　　你到底上哪儿去了？

　　Where in the name of Heaven have you been?