In theory, this problem should not occur, but in reality it does.

从理论上讲，这个问题不应该发生，但实际它却发生了。

youdao

When reality is changing faster than theory suggests it should, a certain amount of nervousness is a reasonable response.

现实的变化速度超出理论预期时，一定程度的紧张倒是合理反应。

youdao

Mutual funds are an excellent idea in theory, but, in reality, they haven't always delivered.

在理论上，共同基金是一个很好的想法，但在现实中，它并不总是能如愿以偿。

youdao

The Elder Brother is issuing this theory without any consideration, - obviously, whatsoever of earthly reality and we're shocked by -- I don't know how else to put it.

大哥没有经过任何思考就提出了这个理论，显然，尘世间的任何事实都让我们震惊了-,我不知道怎么去说。

耶鲁公开课 - 弥尔顿课程节选

Growing that community is still in the early stages, and many of the companies here are trying to find out if that entrepreneurial spirit really exists in reality, not theory.

FORBES: VirtualU in the Startup Ecosystem

Sing, that is, until the music stops, as it did in Europe, and theory meets reality.

FORBES: Election 2012: To Infinity......and Beyond!

But getting tourism money to the poor can be easier in theory than reality.

BBC: How tourism can alleviate poverty